Hey kap'n, this is right up my alley.
I swear by RME gear. It's built like a tank, no flimsy plastic shells, and in my experience they never break down.
Have a bunch of Multifaces that are all still working after 8 years of heavy use, as well as some Fireface 400's that are kicking ever day.
Things to consider about the RME interfaces:
- They make their own low-latency drivers, and update them often. They never, ever crash. Also the firmware has a safety area so you can always backtrack to older firmware if something went wrong during upgrade. Nifty!
- They have word clock input and pass-through so you can use them in professional environments
- The internal clock is super-low jitter and definitely on par with anything that's out there.
- The Fireface 400 will function without external power if you connect it via a full Firewire 400 cable with Macs (not the miniature PC version, that one doesn't pass power)
- The models I mentioned also have an additional 8 In / 8 Out via optical, which can really do wonders when you are interconnecting multiple units (only @ up to 48 kHz) I use mine digitally with TOSLink while word-clocked, never any issues.
- The A/D-D/A converters sound very punchy and clean, two mic pre's on the FF400 are extremely respectable.
- Has built-in MIDI in/out (FF400 has two-in / two out special Mini-DIN to four MIDI connectors)
- Full DSP mixer application, it's pretty straightforward, if you want to get super-fancy you can remote-control the mixer with anything that speaks HUI Protocol like Mackie controllers.
Best of all, if you are using a laptop with PC card slots (PCMCIA), you can find complete Multiface systems on eBay for $250.00 including the PC host card, cable and universal voltage power supply.
Only limitation is 24bit / 96 kHz, that model doesn't go to 176.2 or 192 kHz. (the FF400 does)
There is an option to run those from tower computers with a different PCIe card, as well as for laptops that have a 3/4 ExpressCard slot, but that second option would be making it more expensive. ($500 just for the Express Card adaptor)
There is also a newer model of the Fireface 400 that is hybrid USB / Firewire. Again that's going to be pricey, somewhere in the $1,200 range.
For my money, the deals on the older Multifaces (slate grey front panel) you find on eBay are unbeatable, as long as you don't need mic pre's. Not sexy-looking by today's standards, but will last another 20 years.
If you just want to do TOSLink and no analog besides headphones, there's also another model called 'Digiface' which is excellent for all-digital systems. Again, very cheap on the used market.