Used Akai EIE Pro interface expander, in very good condition.

The Akai EIE PRO (Electromusic Interface Expander) I/O is a tabletop USB audio interface perfectly tailored for your project and portable studio setups. This four-in, four-out (4x4) device enables you on Mac and PC-based systems to record at 24-bit audio resolution at sample rates of 44.1kHz, 48kHz, and 96kHz into virtually any DAW, recording or performance software. The EIE PRO I/O also houses three convenient USB inputs, in addition to its main USB port, enabling you to connect controllers, hard drives or any other peripheral when native ports on a computer may be limited. The compact recording interface contains high-quality components including nickel-plated input jacks, analog-style VU meters and a rugged aluminum casing for a powerful, professional, portable audio solution. 

Each channel of the EIE PRO I/O has an XLR/TRS combo jack, dedicated sturdy, gain-pots and Mic/Line/Guitar switches. The EIE PRO I/O features four discrete-design preamplifiers with 48V phantom power for use with virtually any microphone. Individual 1/4" Nickel-plated jacks found on the back of EIE PRO I/O provide you with channel inserts for processing audio signals externally. You can monitor sessions on multiple sets of studio monitors using the four 1/4" balanced outputs, which are also Nickel-plated. Both pairs of outputs can be monitored visually with the high-quality, analog VU meters providing classic features with modern style. For remote tracking and alternative playback, the EIE PRO I/O has a 1/4" TRS headphone output. High quality analog-to-digital and digital-to-analog converters ensure that every detail of your session or performance gets captured and played back faithfully. 

The EIE PRO I/O sends and receives four audio channels on a single USB cable for simple, universal interface to a computer. The three additional USB ports allow EIE PRO I/O to function as a hub as well, bridging other MIDI controllers and hard-drives to the computer. The USB interface is class compliant for plug-and-play operation with Mac OS X and Windows XP, Vista and 7. The EIE PRO I/O features traditional MIDI In and Out jacks for playing and controlling software with keyboard and pad controllers, workstations, and other MIDI-compatible instruments.