The Echo Digital Audio AudioFire12 is a relatively new device, but comes from a company with a good track record. As with other devices of this calibre, it probably contains far more facilitees than the average VTPO enthusiast will use. Nevertheless, it is well worth considering for our purposes, and lies in the medium to upper price range.
The AudioFire12 has 12 balanced analog inputs and outputs (TRS), 2 FireWire ports, MIDI I/O, word clock synchronization, and 12 channels of full duplex 24 bit 192kHz recording and playback, and has already proved popular with VTPOers for use with GSIF 2.0, MidiTzer and Hauptwerk alike. It requires a 400Mbps Firewire port and will run under MS Windows XP or Vista and happily runs with 44KHz and 48Khz sample rates amongst others. There are currently no drivers available for Linux.
The device is packaged in a case which is capable of being mounted on a standard 19" rack, but it is not know at this time whether it lends itself to being 'stacked' to provide more channels from one PC source. It also comes with a MIDI interface (MIDI in and MIDI out) which is a welcome bonus and can save you the cost of a separate MIDI device.
The Echo webpages list 2 further Firewire devices:
This device has 4 analogue outputs for VTPO use as well as S/PDIF and MIDI I/O.
This device has 8 analogue outputs for VTPO use as well as S/PDIF and MIDI I/O.