Clean Power, Clear Sound: Living With the Fosi ZH3 Desktop DAC and Amp
These go to 99
Once you start exploring desktop audio, it’s easy to fall down a rabbit hole of amps, digital-to-analog converters, and headphones. I’m going to be posting a list of the gear I use regularly, but it’s been nice to explore something new.
The latest bit of gear I got to test was the $199 $159 Fosi Audio ZH3, a desktop DAC designed for headphones and powered desktop monitors. The DAC is on sale now for Black Friday at 20% off.
First, a bit of explanation. A DAC is, as the name says, a digital-to-analog converter. It takes the digital signal from your computer, from iTunes or Spotify, and turns it into an analog signal that real-world gear can use. That signal then goes out through the jacks on the DAC so you can plug in headphones or speakers.
On a basic laptop, this job is handled by a tiny chip on the motherboard. It works, but it is usually noisy and weak. A separate DAC gives that job to a dedicated box with better parts and more power. You get a cleaner signal, more detail, and often less hiss when you turn the volume up. In this case, the DAC is aimed at headphone use, so it is tuned to drive headphones well, with enough power and control for larger or more demanding cans. You can still run it into powered speakers or an amp if you want, but the main goal here is to make your headphones sound like they cost more than they did.
On the back is a set of RCA in for analog sound, a USB-C, coaxial in, and optical in. It also supports a 12V trigger system that can turn all of your devices on and off at once with the right gear. It’s a nice-to-have addition.
Tired of robotic sound and sore ears, I tried the Fosi IM4 and got my music back
I’ve been out of the personal audio space for a bit simply because I thought I found the right mix between comfort and quality. My daily drivers, my AirPods Pro, however, have become problematic. When folks call me, I sound like a robot, which is cool for scam calls but not so great for doctors and probation officers. Further, my
Inside the box, you get a few very interesting chips. The short version is that it is a modern AKM plus XMOS box with a lot of clean power on tap, and it sounds like that reads on paper.
The AKM4493SEQ is one of AKM’s current mid to upper chips. It does Pulse Code Modulation up to 768 kHz and DSD512 and is known for a smooth, slightly relaxed take on neutral rather than a hard, clinical edge. Fosi backs it with an XMOS XU316 USB receiver and four OPA1612 op amps, then feeds the whole thing from a fully balanced dual rail power stage with low noise regulators. That is why they can quote noise down around a couple of microvolts and Signal-to-Noise and Distortion in the 110-plus range on the balanced out.
The interface is quite simple. You tap the volume dial to manage inputs and outputs, and there is some basic treble and base management along with gain. There are some filter modes that change the sound slightly but not in ways you’d expect. This isn’t some kind of Bass Boost button. Instead, it changes the way the DAC handles the audio.
One thing to not: the RCA in — something I use regularly — is limited in volume, which ensures that you’ll probably stick with USB in to maximize the audio headroom.
It also includes a cute little remote control for quick input switching, allowing me to put this thing back into my standard audio chain as needed.
Power is not a problem. The 4.4 mm jack is the balanced output. At 32 ohms, it can give each channel, left and right, up to about 2.5 watts of power. That is a lot for headphones. It means it can drive hard-to-run planars and big dynamic headphones to very high levels without strain.
The 6.35 mm jack is the single-ended headphone output. At 32 ohms, it tops out around 0.64 watts per channel. On paper, that is less than the 4.4 mm balanced jack, but it is still strong enough for most headphones you are likely to own.
For normal dynamic headphones in the 32 to 80 ohm range, that much power gives you a lot of headroom. You can reach very loud levels without the amp sounding strained. With my planar headphones, it still has no trouble. I can turn the volume up to the point where it feels almost uncomfortable, and the sound stays clean. No crackle, no obvious distortion, just more level. That tells you the amp is not running out of steam.
In daily use, you do not need to go anywhere near the limit. A sane setting is around 50 on the volume knob, with your computer’s output set to roughly three-quarters of maximum. That way, the DAC has some room to work, the noise floor stays low, and you still have extra volume in reserve if a track is recorded quietly. If you use very sensitive headphones or IEMs, you will sit lower on the dial, but the idea is the same. Get to a point where the volume feels right, you have some space to move either way, and the sound stays clean and relaxed.
So what does it sound like? These are clean, neutral, and quiet. Bass is tight and controlled, not fat. The middle band is clear and honest, especially with higher impedance cans, and treble reaches up without turning sharp. Some listeners hear a hint of that classic AKM smoothness, a bit more calm than the sharper ESS house style, but nothing syrupy or messy. Stage and imaging are solid, slightly wider on the balanced side, and there is no extra warmth or glare added by the amp itself.
The device can also drive other devices, including powered speakers, but you’re probably going to want to use these for headphones only. I typically use the standard 6.35 mm jack and cable for my headphones, but I’m going to swap out to balanced cables in order to experiment with this DAC.
I’ve been using the XDUOO TA-10R headphone amp for a number of years in a primarily analog way thanks to the way I have my desk set up. That’s a $271 hybrid tube amp that was perfect for everything I did with the headphones, which was some music listening and Zoom calls. This DAC, on the other hand, is inspiring me to try to listen to much more headphone audio, something that the TA-10R never encouraged.
The ZH3 sits comfortably at the entry-level audiophile system. It’s a solid DAC with modern conversion algorithms and loads of power for headphones and speakers. It’s a lot of fun to use, has a clear and open soundstage, and doesn’t mess with the audio beyond conversion and output. At $199, you’re going to get something that will eventually make your cheaper headphones sound pretty bad, which, in turn, will force you to upgrade your cans and then your speakers and then everything else in your life. Until then, you can definitely enjoy this amp without fear of becoming obsolete or missing a single beat.
The AKM4493SEQ breakdown is really helpfull. I've been considering upgrading from my laptop's onboard audio and this makes a compeling case at that pricepoint. The power headrom for planars is particularly intresting since I've been eyeing some harder to drive cans.