If you need to plug USB recording devices to an android, now you can. exTream team has written custom USB driver for USB 1.1 and USB 2.0 class-compliant devices that support with either USB audio spec 1.0 or 2.0. App cost $4. Compatibility list can be found here.
Related item, if you need multi-track mixer. Audio Evolution for Android is the first app that does that. Maybe the two developers can get together and combined these two apps?
Features are: Multitrack audio playback, Audio recording (while playing back other tracks), Loop playback, Import of wav, aiff, flac, Ogg/Vorbis audio files
Mastering to stereo WAV/AIFF/FLAC file, Non-linear non-destructive editing with move, trim, split, cut/copy/paste, remove, range editing
via Google Play