Steinberg UR44

I use this interface in electronic music production home studio. I also like to rip my records in digital format for my personal use and this is where 192 kHz sampling rate is getting in the action. And the 0.1kHz/-0.1kHz frequency response is superb, reproduces an almost colorless sound.
Also comes with bunch of great extras like patented reverb effect and compressor.

As a GNU/linux user I specially appreciated one feature of that unit.
It has a button on the back to make it USB Class Compliant. Therefore this hardware is recognized with no need of drivers or tweak of any kind.
It's totally compatible out of the box.
I'm using it under Debian Testing. It's stable like an Egyptian pyramid. I never had a single crash of JACK. I usually record at 48khz or 96khz. Did a few times at 192 and no problems occured.
Ardour, Hydrogen etc ... I ve encountered no problems with all the software and MIDI also showed perfect compatibility.

Noiseless, the sound is almost crystal clear.

I could not test all the "hardware" effect like reverb etc .... you can use them only under windowsX or maybe macosX as well...
The only disappointing thing, in order to change the entry level of the entry 5 and 6 ( at the back at the unit ) you need to use that software... which is not available on GNU/linux.

I totally recommend it, specially if you're looking for a hardware compatible with GNU/linux.

Very happy with the box. It has 4 similtaneous inputs with preamp, and another 2 with external line level input.
The only issue is that the power supply is EU only (no UK version) but a simple adapter gets round this.

Plug it in and it just works!