Can anyone recommend a multichannel USB audio interface that works with Guitar Tracker. I'd like to be able to record at least 4 tracks simultaneously.
 

 I don't know what Guitar Tracker is but,Guitar Tracks Pro 4 only lets you record 2 tracks simultaniously.You'd have to get Sonar X1 or some other comparable daw to record more then 2 tracks at a time.As far as usb interfaces go,check out M-Audio,Roland,or Focusrite,there are others but I can't think of them right now.The new M-Audio Fast Track C series looks pretty good.