This is a review and detailed measurements of the new Gustard H16 balanced headphone amplifier. It was kindly sent to me by one of their dealers, shenzhenaudio. It has a retail cost of US $399.99 but it is on sale for $363.99 as of this writing.
From the outside, there is nothing that gives away the difference between this high-end headphone amplifier and others:
Rotate the optical encoder on the right though and the chatter of the relays tells you that it is a digitally controlled "R2R" volume control. This assures perfect channel matching as you will see in measurements. For sensitive IEMs, this can be an issue as analog potentiometers are least accurate at their lowest settings. Channel shift can occur as a result which can be annoying.
The rear panel shows that it can be useful as pre-amplifier as well:
You can select inputs and gain setting via short or long press of the center button on the volume control or use the supplied remote control. The remote is another advantage of the digitally controlled volume control.
The H16 is very hefty which I think due to internal toroidal transformer. AC input means doing away with an external power supply which can be substantial in size in some competing products.
Gustard H16 Measurements
Let's start with our usual pass-through test which required use of medium gain (low gain is -6 dB from what I recall):
As noted, that is with balanced input but "unbalanced" 1/4 inch headphone jack. Switching to balanced XLR headphone jack improves performance a bit:
Notice how the mains trace at 60 Hz is highly reduced in level. I would have wanted to see the rest of the power supply spikes to go away as well to match the incredibly low harmonic distortion (down to -140 dB or so). Mind you, the power supply spikes are down to -130 dB which is hugely below threshold of hearing so is not an audibility issue but sheer engineering prowess. As it is, ranking is below top of the class:
Here is our dynamic range which contributes to lower ratings:
Lowering the volume so that the output gets down to just 50 millivolts, gives a middling performance:
It is a bit ironic that the volume control is designed for sensitive IEMs yet the noise level is not as low as it needs to be for that class of device.
Frequency response is as perfect as you can get it up to 100 kHz and likely beyond:
Distortion+noise relative to frequency shows excellent performance, beating once reference Drop THX AAA 789 amplifier:
Power versus distortion and noise is the name of the game in headphone amps so let's jump in there with 300 ohm load, using balanced output:
The low gain mode doesn't seem to be that great. It has slightly lower noise but distorts much earlier. Medium gain seems to be a good everyday setting with high gain reserved for less efficient headphones. Max power while more than enough, loses out to competing products which go as high as 1 watt or twice as much.
My 33 ohm load is only unbalanced:
In high gain mode, we have decidedly higher noise than competing products. Max power is a bit short again but balanced mode is available for more power.
Channel matching as predicted is perfect:
Note that the curve has some discontinuity in it indicating either lack of accuracy in selection of resistors or on-purpose ramping.
Gustard H16 Headphone Listening Tests
As usual I start with my headphone amp killer test which is the 25 ohm, inefficient Drop Ether CX. The H16 drove these like it was child's play. There was incredible clarity, bass and dynamics. I turned up the level to 75 and could not tolerate going higher. There is a ton of reserved, absolutely clean power. If the sound is bad, it is either your music or your headphones.
I did notice a minor issue though: at some increment levels of volume control there is a faint tick. I think this happened between levels 31 and 32 and then in 70s. It is a bit annoying but again, it is faint.
Next test was the Sennheiser HD-650. Despite using the unbalanced 1/4 inch headphone jack, the H16 drove them with absolute authority. At the extreme, the bass was so powerful that it not only gave my ear lobes a tingle but provided a nice skull massage as well! If you want to loose your hearing fast but enjoying it very much along the way, the H16 will do it!
Conclusions
The race in building the most perfect DAC and headphone amplifier has been beautiful to watch. We have achieved what I call "instrument grade" performance, going way beyond any level of transparency we could ever aspire. Tons and tons of power is available which provides incredibly fun moments where you dare to lose a few hair cells in order to have nirvana. What can I say: perfection is what you get. The Gustard H16 delivers on all of these promises in addition to perfect channel matching through its relay controlled digital volume. And ability to use it with remote.
There is a small performance penalty relative to top of the class products here. As a practical matter it does not register but as numbers go, you have given up a tiny bit here and there. And then there is that slight audible ticking sound in the volume range.
I have become such a perfectionist that the above two items kept me from giving the H16 my highest rating. But I ultimately made a call and that was that. Your priority will be different than mine.
Overall, I am very happy to recommend the Gustard H16.
------------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
From the outside, there is nothing that gives away the difference between this high-end headphone amplifier and others:
Rotate the optical encoder on the right though and the chatter of the relays tells you that it is a digitally controlled "R2R" volume control. This assures perfect channel matching as you will see in measurements. For sensitive IEMs, this can be an issue as analog potentiometers are least accurate at their lowest settings. Channel shift can occur as a result which can be annoying.
The rear panel shows that it can be useful as pre-amplifier as well:
You can select inputs and gain setting via short or long press of the center button on the volume control or use the supplied remote control. The remote is another advantage of the digitally controlled volume control.
The H16 is very hefty which I think due to internal toroidal transformer. AC input means doing away with an external power supply which can be substantial in size in some competing products.
Gustard H16 Measurements
Let's start with our usual pass-through test which required use of medium gain (low gain is -6 dB from what I recall):
As noted, that is with balanced input but "unbalanced" 1/4 inch headphone jack. Switching to balanced XLR headphone jack improves performance a bit:
Notice how the mains trace at 60 Hz is highly reduced in level. I would have wanted to see the rest of the power supply spikes to go away as well to match the incredibly low harmonic distortion (down to -140 dB or so). Mind you, the power supply spikes are down to -130 dB which is hugely below threshold of hearing so is not an audibility issue but sheer engineering prowess. As it is, ranking is below top of the class:
Here is our dynamic range which contributes to lower ratings:
Lowering the volume so that the output gets down to just 50 millivolts, gives a middling performance:
It is a bit ironic that the volume control is designed for sensitive IEMs yet the noise level is not as low as it needs to be for that class of device.
Frequency response is as perfect as you can get it up to 100 kHz and likely beyond:
Distortion+noise relative to frequency shows excellent performance, beating once reference Drop THX AAA 789 amplifier:
Power versus distortion and noise is the name of the game in headphone amps so let's jump in there with 300 ohm load, using balanced output:
The low gain mode doesn't seem to be that great. It has slightly lower noise but distorts much earlier. Medium gain seems to be a good everyday setting with high gain reserved for less efficient headphones. Max power while more than enough, loses out to competing products which go as high as 1 watt or twice as much.
My 33 ohm load is only unbalanced:
In high gain mode, we have decidedly higher noise than competing products. Max power is a bit short again but balanced mode is available for more power.
Channel matching as predicted is perfect:
Note that the curve has some discontinuity in it indicating either lack of accuracy in selection of resistors or on-purpose ramping.
Gustard H16 Headphone Listening Tests
As usual I start with my headphone amp killer test which is the 25 ohm, inefficient Drop Ether CX. The H16 drove these like it was child's play. There was incredible clarity, bass and dynamics. I turned up the level to 75 and could not tolerate going higher. There is a ton of reserved, absolutely clean power. If the sound is bad, it is either your music or your headphones.
I did notice a minor issue though: at some increment levels of volume control there is a faint tick. I think this happened between levels 31 and 32 and then in 70s. It is a bit annoying but again, it is faint.
Next test was the Sennheiser HD-650. Despite using the unbalanced 1/4 inch headphone jack, the H16 drove them with absolute authority. At the extreme, the bass was so powerful that it not only gave my ear lobes a tingle but provided a nice skull massage as well! If you want to loose your hearing fast but enjoying it very much along the way, the H16 will do it!
Conclusions
The race in building the most perfect DAC and headphone amplifier has been beautiful to watch. We have achieved what I call "instrument grade" performance, going way beyond any level of transparency we could ever aspire. Tons and tons of power is available which provides incredibly fun moments where you dare to lose a few hair cells in order to have nirvana. What can I say: perfection is what you get. The Gustard H16 delivers on all of these promises in addition to perfect channel matching through its relay controlled digital volume. And ability to use it with remote.
There is a small performance penalty relative to top of the class products here. As a practical matter it does not register but as numbers go, you have given up a tiny bit here and there. And then there is that slight audible ticking sound in the volume range.
I have become such a perfectionist that the above two items kept me from giving the H16 my highest rating. But I ultimately made a call and that was that. Your priority will be different than mine.
Overall, I am very happy to recommend the Gustard H16.
------------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
