FS: Steinberg MR816x multichannel firewire audio interface - $350
I have a Steinberg MR816x that I'm somewhat sadly no longer using - no time, and no appropriate system to use it in. It's a great midrange studio interface and is generally considered the best choice short of the 2k range.
I has 8 channels of analog in/out, plus you can configure 2 stereo pairs of spdif (1 coax and the ADAT port can be reconfigured as spdif as well) for 12 channels. This makes it a great platform for experimenting with digital xovers which is how I used it, or for experimenting with multichannel surround. The analog outputs are actually very very good, but you can throw a DAC or 2 in for the critical channels if you want even higher-grade performance. I used it with Reaper, but JRiver fully supports multichannel ASIO as well and now includes the convolution engine to make it a good xover platform.
One nice feature is that the front panel control knobs can be used as master volume controls - rather convenient and the (digital domain) vc quality is perfectly acceptable in my listening/testing.
I also have the PC that I was using available. This is a vanilla core2duo 6300 (1.8GHz) and is nothing special, except that it has a minimal no-crapware install of WinXP on it, along with a firewire card that works well with the MR816. If you want that along with the interface, I'll include it for an additional $50.
Asking 350 plus shipping. (from 80207).