ART USB Dual TubePre Audio Interface

ART's USB Dual TubePre Audio Interface seems like it would be a great choice for a portable setup especially now that Protools 9 supports any interface. With two tube microphone preamps, DI, Optical Compressor, inserts, SPDIF digital I/O and Latency free monitoring, this USB TubePre packs a lot of features for just $149.
From the website:
"The USB Dual TubePre is the ultimate compact dual channel tube preamp for any basic recording system. Capable of operating as a standalone unit with USB audio interface, or as an expander for any digital system with s/pdif digital input, each channel in the USB Dual TubePre delivers superior tube tone in a fully featured input strip."

Features

• Two channel Tube based Mic/Instrument preamp computer interface
• Extremely low noise discrete front end with variable input and output controls
• Advanced optical output compressor to simplify recording and prevent overload
• USB connectivity to desktop and laptop computers
• S/PDIF output for expanding inputs on digital workstations and computer interfaces
• Latency free Monitoring Mix and Level controls
• Balanced XLR for lo-Z applications and 1/4" hi-Z inputs for instrument DI applications
• Separate Gain, Phase Invert, Low Cut Filter and Compressor switches on each input
• Selectable Dual or Stereo operation of output controls
• Switch selectable Inserts on each channel
• Insert jacks provide a preamp direct out for each channel
• Stereo/ Dual operation of Optical Compressor
• Mono switch for single input monitoring
• S/PDIF Sample Rate switch selectable between 44.1K and 48K
• Precision LED metering of both the preamp and A/D sections
• Built-in low noise +48 Volt phantom power supply
• Compact, stackable all aluminum chassis

$149 at Sweetwater Sound