I use a Behringer QX1002USB mixer. It work fine for direct audio.
-- naught101

I've read different opinions over the last few days. Some say its no problem, others say that now every mixer is suited, while some people say that you should not do this. :-)

-- Quantum_Eraser

To give you an idea of volumes, I run all my audio into a Ginko Synthese Mix, with all the knobs at about 10-11 O'clock (so 1/3?), any higher than about 12 o'clock and I get distortion (not sure if that's in the mix module, or the Behringer, I will have to check.). I run that output into channel 3 of the QX1002USB (this channel as not preamp gain control), and I have that volume at 9-10 O'clock (so, 1/4 volume?). I run the mixer outptut fader at around half for a loudish, but comfortable listening level (studio monitors and a sub in my bedroom). If I play audio from my computer at full volume through one of the other channels, I'd have that channel's volume control at about 12 o'clock.