I have the Volt 2 and use it with Ableton Live for a travel setup. The mic preamps sound nice and clean and I don't have any of the "crackles and pops at buffer sizes above 512" reported by some other folks.
Vintage mode puzzles me a little bit. It's basically a slight "smile" EQ curve with a 0.5dB bump at 50-70Hz and a +2dB shelf at about 8-10kHz or so. A bit more hype is present in the "air" frequencies, it seems to me (another +0.5dB maybe?). There might also be a tiny cut at around 500-600hZ, IIRC. The "warmth" is simply evenly-distributed harmonic distortion once the signal approaches -10 to -8dBFS. And it gets dirty quick up there.
The puzzling bit is that I generally aim for signal peaks of -12dBFS hitting the converters. This means I don't get any harmonic distortion with the Volt Vintage mode when following conventional wisdom around signal levels; just the EQ curve. I have better analogue means to add harmonic distortion at standard tracking levels instead of pounding the converters. Minus 1 star.
All-in-all, it sounds good and works well with Live and the e906, SM57, and K87-based mics I typically use. The Hi-Z input is bog standard and I don't find the Vintage mode to be useful there. Other than the somewhat disappointing Vintage mode, I like it for what it is: a good-sounding, solidly-built interface with a decent form factor for travel rigs. Oh, and a reasonable price for UA kit is rare!