Amplifiers – Page 4 – My New Microphone

In an audiophile's quest to getting the best audio from his pair of headphones, he often encounters a time when a headphone amplifier is necessary. For the regular headphone user, a headphone amp is still a consideration to make when choosing the best headphones for the most desirable listening experience. What is a headphone amplifier and are headphone amps worth it? A headphone amp is a relatively low-powered amplifier that balances the impedance and boosts the voltage of an audio signal to best match the connected headphone in which it sends the audio signal. Headphone amps allow many professional high-impedance headphones to reach their full potential. In this article, we'll describe headphone amplifiers in greater detail and provide you with the information to decide for yourself if a headphone amp is worth it to you. What Is A Headphone Amplifier? Headphone amplifiers, as their name suggests, are designed to amplify audio signals in order to properly drive headphones. A headphone amp connected to a pair of headphones is analogous to a power amplifier connected to a passive loudspeaker. Headphone amps are most commonly found installed near headphone jacks in consumer and professional audio devices. These headphones can be completely analog or they can part of a digital device's DAC (digital-to-analog converter). Note that headphones are inherently analog and require analog audio signals to convert into sound. For more on how headphones work, check out my article How Do Headphones Make Sound? (A Simple Beginner’s Guide). Active headphones, which include wireless and active noise-cancelling (ANC) headphones have built-in amplifiers in their designs. Wireless headphones have receivers to accept the wireless signal and decode the audio signal from it. An amplifier then boosts the audio signal so that it drives the headphone drivers properly. Active noise-cancelling headphones have internal summing amplifiers to adjust the anti-noise signal and combine it with the intended audio signal. These amps are different than what we are typically referring to when discussing headphone amps. Finally, there are standalone headphone amplifier units which are generally the topic of discussion when the term "headphone amplifier" is being used. Standalone headphone amps are common in audiophile and professional studio markets. There are consumer-grade models used by hi-fi enthusiasts and audiophiles and professional audio models, which are typically used in recording studios. Adding an amp between the audio device and a pair of high-end headphones may cause notable improvement in audio clarity, detail and dynamics. On the flip side, failure to do so with certain high-end headphones can lead to poor results in the listener's experience. Headphone amplifiers boost the amplitude (voltage) of the audio signal in order to drive the connector headphones with greater accuracy and power. Amps will also alter the impedance of signals to better match with the connected headphones. To put it simply, headphone amps alter the audio signal in such a way that will benefit the performance of the headphones. The digital-analog converters (DACs) found in some headphone amplifiers work to convert digital audio (the 1's and 0's) into the analog audio (alternating electrical current) required to actually move the drivers and allow them to act as transducers. Headphones need analog audio signal to convert into sound waves and DACs ensure a digital source can properly interact with the headphones. Are Headphone Amplifiers Worth It? Your pair of high-impedance professional-grade or hifi headphones may require a headphone amp to reach their full potential. Similarly, the audio quality may suffer greatly if there is no headphone amplifier to properly adjust the audio signal. Headphone amplifiers are nearly always worth it in these situations. However, they can be very expensive. A related question, therefore is: are expensive headphone amplifiers worth it? Standalone headphone amplifiers have a very wide price range. For example, there's a big difference between the inexpensive ~$20 USD Pyle Pro PHA 40 (link to compare prices on Amazon and B&H Photo/Video) and the ~$32,000 HIFIMAN Shangri-La SR Electrostatic Amp (link to check the price at B&H Photo/Video). Pyle Pro PHA 40 HIFIMAN Shangri-La SR Electrostatic Headphone Amplifier So what makes a headphone amp worth it? Well, first and foremost I'd say the price point must fit within your budget. Next, I'd suggest researching product descriptions, online forums and product reviews to see what model of amplifier best suits your particular headphones. For instance, the aforementioned HIFIMAN Shangri-La SR is wickedly expensive but is meant specifically for ultra high-end HIFIMAN's Shangri-La SR electrostatic headphones. It is not meant to drive high-end dynamic headphones, for instance. To add to that point, the Pyle Pro PHA 40 mentioned above is by no means a high-end amplifier made for hifi applications. Rather its primary function is to provide gain and impedance conversion to a line level signal and split it into 4 different headphone sends. There are plenty of quality headphone amplifiers available for a few hundred or few thousand dollars that may suit your specific headphones perfectly. As discussed at the beginning of this section, a headphone amp is worth investing in if youre headphones require one. The question, then, becomes how much money you're willing to spend. Related article: Are Expensive Headphones (Or Cheap Headphones) Worth It? We'll discuss different headphone amp examples in the upcoming section titled Headphone Amplifier Examples. Headphone Amplifier Specifications Headphone amps, like the headphones they drive, have specifications that tell us about the performance and general characteristics of the device. Common headphones amplifier specifications include but are not limited to: Sample RateBit DepthInputs ConnectorsInput ImpedanceOutputs ConnectorsOutput ImpedanceOutput LevelGainRecommended Load (Headphone) ImpedanceDynamic RangeFrequency ResponseSignal-To-Noise RatioCommon Mode RejectionCrosstalk / Channel SeparationTotal Harmonic DistortionMax PowerNoise FloorPower SupplyPower ConsumptionDimensions/MassOperating TemperatureOperating Humidity Let's briefly define each of these specifications in order to better understand headphone amplifiers. Sample Rate Support Many headphone amplifiers double as digital-to-analog converters (DACs). When sending digital audio to a headphone amp DAC, it's important to match the sample rate of the digital audio signal to the sample rate the DAC expects. Failure to do so may result in degraded audio quality. Sample rate is measured in kHz (thousands of samples per second) with common digital audio rates including 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz, 186.4 kHz, and 192 kHz. Note that the sample rate has to do with the digital audio signal at the DAC input. Headphones are inherently analog and require analog audio signals to drive them. Bit Depth Support Digital audio is also defined by bit-depth and so headphone amps with DACs will also need to support the bit-depth of the incoming digital audio signal. Bit-depth is measured in bits (common digital audio values include 16-bit and 24-bit) and refers to amount of potential amplitudes each sample of the digital audio signal may have. Inputs Connectors There are plenty of audio devices that we may want to listen to via headphones that require a headphone amp to do so. The connectors of these devices vary from model to model and headphone amps may have different input connections to make them more versatile (and rid of the need for adapters). Common input connectors include but are not limited to: USB-AUSB-BOpticalCoaxialRCAXLR balanced3.5mm (1/8") TRS stereo6.35mm (1/4") TRSBluetooth Wireless Input Impedance Each input of the headphone amp will have its own impedance rating, measured in ohms (Ω). Any given input of a headphone amplifier will act as the load to the connected audio device. To achieve optimal signal flow from an analog sound source to an analog input, the load impedance (the input impedance of the amp) must be significantly greater than the source impedance (the output impedance of the audio source being sent to the amp). Though there's no set standard, it is commonly accepted that a load impedance 10 times that of the source impedance should yield sufficient signal transfer. That being said, the greater the difference, the better, in theory. Different input connector types will have impedances in different ranges. For example, the RCA inputs expect consumer line level signals (nominally −10 dBV) and typically have an input impedance between 10 kΩ to 50 kΩ. Note that input impedance only really applies to wired analog connections. Hardwired digital and wireless connections are not overly concerned with impedance bridging. I've assembled the following table to show the typical impedance values of different input and output signal types: Input/Output TypeTypical Impedance RangeTypical Voltage Range (Nominal) Mic Level Output50 Ω to 600 Ω-60 dBV (1 mVRMS) to -40 dBV (10 mVRMS) Mic Level Input1.5 to 15 kΩ-60 dBV (1 mVRMS) to -40 dBV (10 mVRMS) Instrument (Hi-Z) Level Output10 kΩ to 100 kΩ -20 dBu (77.5 mVRMS) Instrument (Hi-Z) Level Input47 kΩ to over 10 MΩ-20 dBu (77.5 mVRMS) Line Level (Professional) Output75 to 600 Ω+4 dBu (1.228 VRMS) Line Level (Professional) Input10 kΩ to 50 kΩ+4 dBu (1.228 VRMS) Line Level (Consumer) Output75 to 600 Ω-10 dBV (316 mVRMS) Line Level (Consumer) Input10 kΩ to 50 kΩ-10 dBV (316 mVRMS) Speaker Level Output10 kΩ-10 dBV (0.300 VRMS) Headphone Jack Output0.1 Ω to 120 ΩN/A Headphone Input8 Ω to 600 ΩN/A Outputs Connectors Just like there are various connectors to link audio devices to headphone amps, there are various connection types between the headphone amps and their headphones. Common headphone amp output connectors include but are not limited to: XLR-3XLR-4 balanced3.5mm (1/8") TRS stereo unbalanced6.35mm (1/4") TRS stereo unbalancedRCA It's critical that we match the wiring schematic between the headphone amp out and the headphones in question. For example, the XLR-4 balanced has the following wiring/pinout standard: Pin 1: left channel (positive polarity)Pin 2: left channel (negative polarity)Pin 3: right channel (positive polarity)Pin 4: right channel (negative polarity) This would not be capatible with the commonly-used unbalanced stereo TRS wiring/pinout standard which is as follows: Tip: left channelRing: right channelSleeve: common return and ground These two standards are incompatible and this incompatibility should be thought about when making purchasing decisions about headphones and headphone amplifiers. Output Impedance The outputs of the headphone amp, which connect to the headphones, will have impedance values, measured in ohms (Ω). Typically these impedance values are between 0.5 Ω to 120 Ω with lower values generally considered better. In the case of the connection between the headphone amp and the headphones, the amp becomes the source and the headphones are the load. Having a load impedance greater than 8 times the source impedance yields a damping factor of 8:1 and allows the headphones to perform well. That being said, impedance bridging may be improved with a ratio greater than that while a ratio lower than 8:1 can still yield good results. Most headphones have impedance ratings in the range of 8 Ω to 600 Ω. For more on impedance matching, skip ahead to the section titled What Is Headphone Impedance? Gain Gain refers to the maximum amount of gain the amplifier may apply to the signal. In other words, the amount the amp can boost the amplitude of the signal from the input to the output by supplying electrical energy. Gain is measured in decibels and most headphone amplifiers will have a potentiometer to adjust the gain applied to the input signal. Dynamic Range The dynamic range, measures in decibels, refers the difference between the loudest and quietest signal levels the amplifier is capable of outputting. Frequency Response Frequency response refers to the audio frequency range the amplifier is capable of producing. Ideally, the manufacturer will provide a range with a level variation within that range (ie: +/− 0.1 dB), though this variation isn't always included. The frequency response spec complete with the amplitude variation tells us how accurately the headphone amp will reproduce the inputted audio signal. Note that headphones also have their own frequency response that effectively colour the audio signal. However, when it comes to amplifiers, it's important that the amp does not overly colour the original audio signal. For more information on headphone frequency response, check out my article What Is Headphone Frequency Response & What Is A Good Range? Common Mode Rejection The inputs of headphone amplifiers are often balanced and offer common mode rejection. Put simply, common mode rejection is the amp's ability to eliminate any electromagnetic interference and noise from the signal that was picked up during transmission for the audio source to the amplifier. Crosstalk / Channel Separation Crosstalk happens when any amount of the signal meant for the left headphone driver gets into the right headphone driver and vice versa. Crosstalk is measured, in decibels, at various individual frequencies. It is caused by unbalanced headphone signal transfer in which the left and right channels share a common ground/return wire. Simplified Unbalanced Headphone Schematic Total Harmonic Distortion Total harmonic distortion (THD) is one way to describe the propensity for headphones to distort. THD is measured as a percentage of harmonic distortion at a single test frequency (typically 1 kHz). It is defined as the ratio of the sum of the powers of all harmonic components to the power of the fundamental frequency. Note that different manufacturers measure their headphones' THD at varying signal and/or sound pressure levels and so it's sometimes difficult to compare headphones in terms of their THD values. Max Power The maximum power of a headphone amplifier is the maximum electrical power the amp is capable of outputting to its connected headphones. It is measured in watts (more commonly in milliwatts). It's important to note that the [load] impedance of the headphones is a factor in determining the power of the headphones and so, generally, manufacturers will give us multiple specifications for max power. Noise Floor / Signal-To-Noise Ratio Noise floor refers to the amount of noise the amplifier will add to the audio signal it sends to the headphones. Because headphone amps are active unit that provide gain to their audio signals, they will all introduce some noise to the signal. Noise floor is typically given as a negative dBV (decibels relative to 1 volt) value though it may be given in V or mV as well. Alternatively, manufacturers will provide a signal-to-noise ratio rating which is measured in dB or dBA. This refers to the difference between the signal strength and the noise strength, measured in decibels. Different headphones amp outputs may present different noise ratings. Power Supply This simply refers to the PSU that will convert the power from the electrical mains into the appropriate voltage and power to run the amplifier. Power Consumption This refers to the amount of power required for the amplifier unit to run. Oftentimes there will two ratings here: one for standby and one for operation. Power consumption is measured in watts. Dimensions/Mass The length, width, depth and weight of the physical amplifier. Operating Temperature The temperature range in which the amplifier will work properly. Operating Humidity The relative humidity conditions in which the amplifier will operate proficiently. Built-In Amps In Headphone Output As we've discussed, headphone amplifiers are not only found the standalone units that are obviously titled headphone amplifiers. They are also found inside each and every headphone jack. These jacks are part of many common devices including: MP3 playersSmartphonesLaptopsTabletsAudio interfacesRecording devicesMixing consolesTape playersCD players These amps often have DACs (digital-to-audio converters) to convert the digital audio to analog audio in order to drive the headphone drivers. Headphone jack amps range in quality but are nearly all of poorer quality than the standalone amplifiers we're focusing on in this article. Headphone jacks are often only capable of driving low-impedance headphones. Many professional and hifi headphones are designed with higher impedances and would not perform at their potential if connected to a regular headphone jack. This is due to the size/space and power limitations of the headphone jack amplifiers. They must fit within the device and be in close proximity to the jack while also working on the power source of the device (often batteries). That being said, there is certainly a market for high-end low-impedance headphones that will work effectively with our portable devices and their headphone jacks. For more information on headphone outputs, check out my articles Are AUX (Auxiliary) Connectors & Headphone Jacks The Same?, Differences Between 2.5mm, 3.5mm & 6.35mm Headphone Jacks and How Do Headphone Jacks And Plugs Work? (+ Wiring Diagrams). Reaching The Full Potential Of The Headphones Speaking of reaching the full potential of our headphones, let's discuss how headphone amplifiers help us to get the most out of our headphones. Well, as mentioned, the built-in headphone jack amplifiers are often not powerful enough to drive high-end headphones. Amplifiers need to deliver enough power to properly drive the headphones with clarity and precision without causing distortion at the peaks of the amplified audio signal. Let's first look at the headphones that would likely require amplification. There are plenty of factors that would allow headphone audio quality to be improved by an amp. The two most important factors are efficiency/sensitivity and impedance. What Is Headphone Efficiency/Sensitivity? Headphone sensitivity (sometimes called efficiency) is the relationship between the power of the audio signal sent to the headphones and the loudness of the resulting sound produced by the headphones. This rating should ideally be presented as a sound pressure level (in decibels) per 1 milliwatt of signal power (dB SPL/mW). The more sensitive a pair of headphones, the more sound volume they'll produce at a certain signal strength. Generally speaking, headphones with a sensitivity rating of 95dB or less are more likely to require a headphone amp. That being said, the sound of headphones with higher sensitivity ratings may very well be improved with an amplifier as well. Note that the amount of power a headphone amplifier is capable of providing its connected headphones is a product of the headphones' impedance. Higher impedance headphones tend to require more power in order to produce the same amount of sound. The benefit that comes with higher impedance and requiring more power is that the headphones tend to sound more accurate. To learn more about headphone sensitivity, check out my article The Complete Guide To Headphones Sensitivity Ratings. What Is Headphone Impedance? Headphone impedance is essentially the measure of the headphone drivers' resistance to the audio signal driving them. Impedance values are given in ohms (Ω). All else being equal, higher impedance headphones ought to be less sensitive than lower impedance headphones since their drivers require more power to be driver effectively. However, headphone design plays a big role in determining these stats and there is no correlation between impedance and sensitivity across different headphone designs. Generally speaking, headphones with a higher impedances require stronger signals to driver their drivers. Though any headphones could be hooked up to an amplifier (connection types permitting), those with higher impedances would likely benefit more from an amplifier than those with lower impedances. Although there are no set rules, headphones with impedances over 80 Ω will generally benefit from a headphone amplifier. The increase in voltage provided by the amplifier gain will allow the audio signals to drive the high-impedance driver with more power, precision and volume. As another general rule, the headphone (load) impedance should be at least 8 times the output impedance of the amplifier (source). To learn more about headphone impedance, check out my article The Complete Guide To Understanding Headphone Impedance. Balanced Headphone Signals Some headphone amps also provide balancing in case the high-end headphones are balanced as well. Balanced headphones have the following advantages over unbalanced headphones: No crosstalk since there is no common ground/signal return wire.Doubling of voltage applied to the driver which improves clarity and amplitude. That being said, if the headphones are unbalanced, there is really no advantage here. Electrostatic Headphone Amplifiers/Energizers Electrostatic headphones are a special breed. These headphones, as their name suggests, work on electrostatic principles. The electrostatic headphone driver has a positively charged diaphragm placed between two stator plates that act as sort of parallel plate capacitor. The audio signal is applied to the stator plates which effectively complete the circuit. As one stator plate receives a positive voltage from the signal, the other stator plate received an equal but negative voltage. The audio signal effectively charges the stator plates which causes the diaphragm to move back and forth due to attraction and repulsion. STAX SR-007A MK2 Electrostatic Headphones The STAX SR-007A MK2 is featured in My New Microphone's Top Best Electrostatic Headphones. In order for the driver to work properly, it has a wildly high impedance. This helps to mitigate any stray voltage from the plates. Thus, in order to properly drive the electrostatic driver, a very high voltage is required at the stator plates. These high-voltage signals have very low currents and are achievable via specialized electrostatic headphone amplifiers/energizers. On top of that, the electrostatic amp/energizer may also need to provide the bias voltage required to charge the diaphragm. Simplified Electrostatic Headphone Driver Schematic With Amplifier The STAX SMR-007TII (link to check the price on Amazon) is a well-known electrostatic headphone amp that works well with the famed STAX SR-007 (link to check the price on Amazon) headphones. STAX SMR-007TII This tube amplifier has 3 inputs (1x XLR and 2x RCA) with 1x RCA parallel output and two headphone outputs with Molded 5-pin connectors for use with STAX headphones. The SMR-007TII has an incredibly high input impedance of 50 KΩ (100 kΩ when balanced). Its rated input level is 200mV with a maximum input level of 30V rms at minimum volume. This model provides 54 dB (x500) of gain to the signal and has a maximum output voltage of 340V rms at 1 kHz. The SMR-007TII also provides 580V (x2) as a biasing voltage for the electrostatic headphone drivers. To learn more about active headphones like the electrostatic headphones described above, check out my article How Do Headphones Get Power & Why Do They Need Power? Stax is featured in My New Microphone's Top 13 Best Headphone Brands In The World. Active Noise-Cancelling Headphones Have Built-In Headphone Amps Active noise-cancelling (ANC) headphones need amplifiers to function properly though these amps are not the same as the amps we've been discussing thus far. Rather, the built-in amplifiers in ANC circuits are tasked with the following: Amplifying/processing the noise-cancelling microphone signal in order to produce the anti-noise signal.Summing the intended audio together with the anti-noise signal. Note that, generally speaking, the ANC headphones, when wired, rely on the amplifier of the headphone jack or the standalone amplifier to boost the "intended audio" signal to the appropriate level. For more information on active noise-cancelling headphones, check out my articles How Do Noise-Cancelling Headphones Work? (PNC & ANC), Passive Vs. Active Noise-Cancelling Headphones and Do Noise-Cancelling Headphones Work With Or Without Music? Wireless Headphones Have Built-In Headphone Amps Wireless headphones receive their audio signals wirelessly. Let's briefly discuss how they work. The intended audio signal, whether analog or digital, will be encoded into a wireless format (either a radio frequency signal, including Bluetooth, or an infrared signal) by a transmitter. The transmitter could be a standalone device or it could be built into the audio device. Bluetooth wireless, for example, is a standard protocol that many digital devices have to transmit digital audio wirelessly via radio frequencies in the range of 2.400 to 2.485 GHz. The wireless receiver, which is built into the headphones themselves, decodes the audio signal from the wireless signal for the headphone drivers to convert to sound. Before the audio signal is sent to the drivers, it passes through a DAC and/or amplifier. These devices will convert digital signals to analog if need be. They will also provide the appropriate amount of gain to the signal and be designed for optimal impedance matching with the headphone drivers. To learn more about wireless headphones, check out the following My New Microphone articles:• How Bluetooth Headphones Work & How To Pair Them To Devices• How Do Wireless Headphones Work? + Bluetooth & True Wireless Headphone Amplifier Examples To better understand headphone amplifiers, let's look at some examples. We've already mentioned several. Here are a few more: Behringer Microamp HA-400FiiO Q5sRupert Neve Designs RNHPAudio-Technica AT-HA5050H Behringer Microamp HA-400 The Behringer Microamp HA-400 (link to compare prices on Amazon and B&H Photo/Video) is an inexpensive, miniature 4-channel headphone amplifier designed for stage and studio application. The unit is equipped with separate operational amplifiers for each channel, and individual channel level controls. Behringer HA-400 This simple analog headphone amp features 1x 6.35mm (1/4") TRS input jack that feeds 4 separate op-amps for 4 individual 6.35mm (1/4") TRS output jacks. The frequency response is 20 Hz - 20 kHz which seems like a small range compared to most high-end amps but is perfectly matched to the audible frequency range. FiiO Q5s The FiiO Q5s (link to compare prices on Amazon and B&H Photo/Video) is an example of a portable headphone amplifier with Bluetooth connectivity. FiiO Q5s FiiO is featured in My New Microphone's Top 11 Best Headphone Amplifier Brands In The World. On top of portability and Bluetooth connectivity, the Q5s is modular and fully compatible with FiiO amp modules for enhanced sound and outputs. The AM3E amp module supports 2.5mm, 4.4mm (Pentaconn) and 3.5mm headphones and the DAC clock system supports up to 768 kHz/32-bit decoding. Digital audio can be sent to the amp via 3.5mm (1/8") analog line; USB; SPDIF, or Bluetooth with the following specs: USB: 768 kHz / 32-bitCoaxial: 192 kHz / 24-bitOptical: 96 kHz / 24-bit The rated headphone impedance of the Q5s amp is 16 to 150 Ohms (unbalanced) and 16 to 300 Ohms (balanced). Connecting headphones with the following impedanced will yield the best results with this amplifier. Rupert Neve Designs RNHP The Rupert Neve Designs RNHP (link to compare prices on Amazon and B&H Photo/Video) is a popular high-end single-output desktop headphone amplifier that goes for a relatively affordable price. Rupert Neve Designs RNHP This precision analog headphone amplifier offer incredible wide-open sonic performance with the ability to drive any pair of headphones up to 600 ohms. It features 3 different inputs along with a single 6.35mm (1/4") headphone output jack. The inputs are: 2x XLR/TRS Combo jack (left and right): balanced line input2x RCA (left and right): unbalanced consumer line input1x 3.5mm: unbalanced stereo mini-jack input The single 6.35mm (1/4") headphone output jack has an extremely low impedance of .08 Ohms which is low enough to drive even the lowest-impedance professional headphones with excellent clarity. This headphone amp is very accurate with a frequency response of 10 Hz to 120 kHz (+/- 0.2 dB). Audio-Technica AT-HA5050H The Audio-Technica AT-HA5050H (link to compare prices on Amazon and B&H Photo/Video) is an expensive hybrid headphone amplifier capable of driver 8 headphones of varying impedances (rated 16 - 600 Ohms). Audio-Technica AT-HA5050H Its hybrid amplifier circuits include tube electronics (2x E88CC tubes) at the preamp stage and solid-state electronics (2x Toshiba bipolar power transisitors) at the power amplifier stage. This amp is also capable of wokring with both analog and digital audio inputs due to its high-quality DAC. The inputs of the HA5050H include: 2x RCA: line input2x XLR: balanced1x USB-B: digital1x Coaxial (SPDIF): digital The DAC is optimized to be compatible with digital audio formats up to PCM 32-bit/384 kHz and DSD128. Of the 8 headphone jacks, there are 4 different impedance ratings that apply to 2x 6.35mm (1/4") jacks each. They are: 0.1 Ω33 Ω82 Ω120 Ω Other notable specifications include: Frequency response: 5 Hz - 200 kHz Max Power: 2,000 mW + 2,000 mW (16 Ohms load)1,000 mW + 1,000 mW (32 Ohms load)500 mW + 500 mW (64 Ohms load)62 mW + 62 mW (600 Ohms load) Related Questions Do you need an amp for 80-ohm headphones? Headphones with a rated impedance on 80 ohms fall into a sort of grey area when it comes to their amplification requirements. These headphones do not necessarily require an amplifier and will sound good if the headphone jack is of high quality. However, providing them with a quality amplifier will likely improve their sound. What is a DAC? DAC is an initialism that stands for "digital-analog converter." As their name suggests, DACs work to convert digital audio from a digital device into analog audio that is often sent to a transducer (headphones, loudspeakers, etc.) to be converted and propagated as sound.