Adjusting the gain of your digital-to-analog converter (DAC) or amplifier is a necessary step in tuning your sound and volume, but picking a setting that’s too high is an easy mistake for a budding audiophile to make. Gain is often confused with loudness and volume. Instead, gain settings determine how your DAC, amplifier, or receiver delivers power to your output earbuds, headphones, or speakers. Volume strictly handles loudness, whereas gain can actually boost the strength and power of the electrical signal reaching your audio outputs.
Pick a gain level that’s too high, and your amp could be raising its noise floor and introducing distortion in exchange for no sound quality benefit. This fact leads many to leave their gain setting on “Low” and ignore it, but that isn’t the right answer either. You should adjust the gain of your DAC based on the impedance and sensitivity of the headphones you want to drive. I’ve been testing the Fiio K15, a mid-tier DAC with five gain levels, and changing the gain setting finally made my Sennheiser HD 600 headphones sound how they should.
Gain doesn’t just affect the volume level
It delivers more power to your earbuds, headphones, or speakers
People have a tendency to incorrectly correlate louder music with higher-quality music. In reality, extreme loudness only damages your hearing — it doesn’t actually make anything sound better. The gain setting on your DAC or amp controls how audio is amplified before it reaches your headphones, and it affects loudness, but that’s not all it does.
Since gain alters amplification rather than loudness, switching a gain setting changes the volume level dramatically. You’d have to fully rotate the volume knob multiple times to match the loudness increase caused by flipping the gain switch once.
The key difference between gain and volume is that the former adjusts the electrical strength of an audio signal at the input stage by increasing its voltage, whereas the latter boosts the loudness at the output stage. There are two kinds of gain: hardware gain and software gain.
Hardware gain changes the amplification at the hardware circuit level, while software gain adjusts the output volume using algorithms. So, one kind of gain behaves similarly to the volume knob, and another physically increases the voltage of a signal as it enters your DAC or amp.
You should consult your audio equipment manual to understand your DAC or amp’s gain levels and how they are achieved. For example, the Fiio K15 I’m testing has five gain levels: low, medium, high, super high, and ultra high. However, the first three gain levels are hardware low gain modes, and the medium and high settings are using software gain.
The super-high and ultra-high gain modes use hardware gain, applying up to 12dB of extra amplification to a signal. This explains why switching from low to medium or high had little effect on the sound, but flipping the switch to super high made a noticeable impact.
Why some headphones need a higher gain setting
Gain is often misunderstood as a way to quickly raise your output volume, but it serves a different purpose entirely. Hardware gain amplifies the electrical signal directly, which allows your DAC or amp to power high-impedance headphones. These headphones require more power — in other words, a higher voltage — to output volume at comfortable listening levels.
This is why high-impedance headphones sound weak, quiet, or compressed straight out of your laptop’s 3.5mm headphone jack. It doesn’t have the power to adequately drive those headphones, and you’re not enjoying their proper frequency response due to dynamic compression. Think about how audio drivers work. They physically move to produce sound, and without a strong or powerful electrical signal, they can’t move enough to sound as expected.
Dynamic drivers in particular do not have a flat impedance curve. Frequency levels can have different impedances at the same gain level. If the gain is set too low, sounds that exist in the dips of a dynamic driver’s impedance curve might be inaudible. Setting the gain higher amplifies the entire impedance curve, surfacing sounds in music that could easily be missed at lower gain levels. It’s how your high-impedance headphones sound different at higher hardware gain levels, even though gain isn’t directly changing the frequency response or sound signature of your outputs.
Instead, higher gain levels simply give your headphones enough power to sound how they should at their best. For example, my go-to open-back headphones, the Sennheiser HD 600, have a tricky combination of a higher impedance (300 ohms) and a low sensitivity (97dB) that makes them harder to drive. These aren’t the highest-impedance headphones you’ll find, but using the Sennheiser HD 600 cans with the Fiio K15 set to low gain, I need to crank the volume up near the maximum. Remember, this is changing the loudness at the output stage.
Switching to the super-high gain mode and leveraging hardware gain lets me keep the output volume at around the halfway point. The higher voltage of the electrical signal reaching the headphones makes them sound richer and more dynamic, as every part of the frequency response curve is getting the power it needs. Plus, when I switch to low-impedance headphones like the 32-ohm Fiio FT13, I can easily move the gain to the low setting without having to touch the volume knob.
Use the lowest gain setting you can get away with
You should increase gain out of necessity, not to improve sound quality
When playing with the gain switch, there’s one rule of thumb to know. You should always use the lowest gain setting possible for your headphones. If you’re listening with low-impedance headphones like the Fiio FT13 or a pair of in-ear monitors (IEMs), you shouldn’t need to move the gain level above the low setting. Adjust volume before moving the gain switch, and only do the latter as a last resort. You’ll want to change the gain setting when the current level can’t produce the volume level you need.
Raising the gain level before it is necessary also raises the noise floor, and can create unwanted effects like clipping and distortion. It can also harm your hearing or damage your equipment. For high-impedance or low-sensitivity headphones, though, adjusting the gain setting on your DAC is a necessity. These headphones need a boosted electrical signal to be driven properly, and produce the sounds you expect.
- Color
-
Black, Silver
- Bluetooth
-
Bluetooth 5.1 (LDAC/aptX Adaptive)
- Wi-Fi
-
2.4G/5G dual-band (and Gigabit Ethernet)
- DAC
-
Dual AK4497SVQ DACs
- Amplifier
-
3000mW x2 Balanced Power
The Fiio K15 is a powerful desktop DAC and amplifier with a small touchscreen and a variety of audio inputs and outputs. The amplifier supports dual-band Wi-Fi and hardwired Gigabit Ethernet connections. It can be used with digital, analog, and optical inputs, as well as for streaming as a Roon Ready endpoint and AirPlay-compatible receiver.
