I used this in my studio. It's fully functional.
Below is the specs from the ART manual.

DIGITAL MPA FEATURES:
• Variable input impedance for flexible microphone voicing (150 Ohms to 2400 Ohms).
• Selectable plate voltage
• Large VU meters
• Front accessible meter trim
• Selectable between output level and tube warmth
• Improved discrete class A input microphone preamplifier
• Lower noise at low gains
• Lower THD
• Wider frequency response
• Front accessible Instrument Input Jack
• Very high input impedance
• Automatically switches to the instrument input when you plug in
The Digital MPA also features digital connectivity for use with various digital processors and digital recording devices. The Digital interface supports the following features and functions:
• 24-204KHz External sample rate
• 44.1K, 48K, 88.2K, 96K, 176.4K, 192K Internal sample rates
• 24/16 bit switchable dithering
• Wide dynamic range A/D
• Rotary Encoder for quick selection of sample rate and output format
• Separate analog and digital output level controls
• Digital Level LED meters
• ADAT optical I/O
• Sync to incoming ADAT data rate
• Switch selectable optical output (S/PDIF or ADAT)
• Selectable Pro/consumer output format
• AES/EBU output on cannon connector
• Two wordclock jacks allowing loop through

Call Tom at 805-659-1930