Both the Motif ES and Pa1xpro have USB AND Midi interfaces. The Pa1xpro also includes an SPDIF output, ie., [Digital Output]. The Motif ES has an "option" to add a SPDIF connection by way of an 'add-on' Board.

New Yorker: You can still use a PCI Sound Card by simply running the Pa1xpro or Motif ES's 'Main Outs' to either a MIXER 'then' to the PC/MAC or with some Sound Cards 'directly' to the Sound Card and then into the PC/MAC.

USB 2.0 or Firewire interface Sound Cards only "benefit" when the PC/MAC "also" have USB 2.0 or Firewire interfaces, ie., "high speed" Bus connections. So the Computer will need to be USB 2.0 or Firewire capable.

Midi In/Outs are only used for Midi data NOT Audio. So you wouldn't be able to use the Midi In/Outputs for recording Audio.

Best regards,
Mike