Probably out of your price range, but this looks really sweet: MOTU 2408 Core MkIII PCIe System I know I didn't help. But it looks like the right direction. If you're in the US, you might want to call Sweetwater and get some direction. They are usually pretty cool about helping.
Unfortunately the MOTU is way out of my price range.
It's really sad, nothing wrong with the 2496. It's absolutely the most reliable and trouble free piece of computer hardware I have ever owned. Wish high end MOBO's offered PCI!