In theory, if you have a fully compliant USB Class 2 driver loaded on your computer, it should work fine with the Lynx Hilo. The reality is apparently a bit more complicated than that.
Where are you located? If you're in SoCal, I'm going to be gone from lunchtime on Thursday until late afternoon on 11/30, and you could borrow my Hilo to play with.
Hilo itself is not compliant. For example, it reports no sample rates for any of the clock sources via the USB Audio Class 2 RANGE command. It might have more than one selectable "compatibility" mode there though, I'll have to check that out vs Windows. Perhaps the lower or higher ones tweak the LT-USB card itself.
It doesn't use or work with the standard USB Audio driver by the way.
I do have the newest firmware for both LT-USB and Hilo itself. I don't need another one, I have one already and I'm kind of loathe to return it, since it works perfectly fine in Windows (with the included driver) and on Mac (with the included driver).
Therefore, I just get to sniff the Windows driver and see what it does. Perhaps it's just a hardcoded list of sample rates (or a range, more likely, it might support every sample rate, I've seen it sync on 2000 Hz clock signal; it's better at audio frequency clock sync than our best scope) or some proprietary silly command.
RE: AMB Gamma 2: I thought a while and that's the one I'd recommend.
Most everything else is either a portable DAC/AMP like FiiO E7/E07k/E17 and/or bit limited on DAC front like Leckerton UHA-6s. Pity I cannot live without a few ADC and that's a much tougher problem in Linux.
(There are a few simple USB audio devices with ok 16-bit DAC/ADC, but nothing really good.)
