M-Audio have a [[http://www.m-audio.com/?do=products.family&ID=midiinterfaces|range of MIDI interfaces]] with up to 4 in/out.

2x2 and 4x4 Anniversary models reported working on [[http://linuxmusicians.com/viewtopic.php?f=6&t=11054&sid=dd7bf8f15b96f031b406a390459c2acc|forum]]

See also [[M-Audio Uno]]