Well, first I must say that I felt very depressed unboxing the THX AAA portable due to the commments and reviews I had read on ASR forum, the jist of which is that this device has a hiss and background noise that’s unbearable, just plugging your headphones is enough to make your ears bleed. I was so excited after watching Zeos review this Dac/Amp that, as happens way too often, I went and ordered mine with joy in my heart. That joy died a bloody death with those comments.
Now, after spending hours with the THX AAA trying various sources and outputs and things like; powering on with earphone plugged in or not and DIRC on while powering or not, etc… etc, I can tell you that, yes, there is a bit of noise present with iems starting fat -5.0dB all the way up to full volume ay +16.0dB. With just the earphone in, there’s nothing, it shows up when you plug in the LINE In or the USB input (tried various interconnects including Fiio L-19 to BTG mini cable). But no hiss, it’s more like the background you hear from a record player but wouldn’t call that a hiss nor would I say it’s audible with music playing. Remember that, what I’m describing is only with IEMs at very high volume, damage your earing volume. With headphones, it’s clean, nohiss no noise.
To dismiss the THX AAA portable because of a noise you can’t really hear in normal listening condition is ridiculous. This is a clean, precise, powerhouse of a device with great features like DIRAC, DRC, a whatever you want EQ. USB C would have been nice, auto-shutdown too and I’m sure I’ll find a couple other kinks in it’s armor (certainly not in it’s build which is like a tank with a little bit of leather) but as of now, this is my go to portable and if I didn’t have a desktop setup, this would do the job
there perfectly too.
but that’s just me…