The K-MIX from Keith McMillen is a great little mixer, audio interface, midi controller combination box. Here's an introduction to how you can use it without any computer involved. Mix, set up the trims, aux sends, EQ etc. You can totally use it stand-alone, but there are additional features such as surround mixing, low cut, USB Pro/ post, linking tracks in stereo pairs etc. These additional features can be set up from the computer, stored on the K-mix, then used in stand-alone mode.

Cuckoo Music: K-Mix Review part 1, Standalone Mixer mode More Press & Reviews