Mackie ProFX12 Reviews
Yes, this mixer has USB out and in, so can be used as an 2-channel interface (pan one signal left, the other right). I have read that there can be an annying high-pitched sound when using this as interface, and I noticed it on a computer-to-mixer USB signal when I turned the control volume way up to monitor something, but when kept at half-way, could to hear it. I have not used it (yet) for sending signals to the computer, so can't comment on that.
I bought it to keep all my instruments and mics plugged in for recording to a stand-alone digital recorder (I use the tape outs), and this works great for this purpose. Phantom power and preamps all are are good.
For mixing, there are EQ controls for each channel, as well as a multi-band main equalizer. The "FX" are pretty limited but should provide adequate reverb for live band use, and there are spearate monitor and main outputs and controls. All you need are some active PA speakers and monitors and you should be all set to go
12-channel Compact Mixer with 3-band EQ per Channel, Built-in Effects, 4 Stereo Channels, and USB I/O