michael japanFor the record, there seem to be serious issues with the presonus 1818vsl.
I had the hots for the 1818VSL to replace my E-MU 1820m, but couldn't get over the poor latency performance. Even for folks who manage to get it to run with smaller buffers, the"hidden" latency in the USB and A/D/A sections is high so that the overall latency suffers.
You mentioned MOTU, and I see the 828 in your signature. I ended up with a used 2408mkII/PCIe-424 combo that is handling the same project load at 64 samples (4.5ms round-trip) that the E-MU (PCI) did at 96 samples (6ms round trip). This is with the ASIO driver.
The 1818VSL and 2408mkII/III were on my short list for including ADAT input that I needed for one of my keyboards. The major missing features on the 2408 are mic/instrument preamps and MIDI I/O, but I already have other gear for that.
Anyway, I hope you get the 1818VSL working to your satisfaction. If you haven't already tried it, I second daveny5's suggestion to try the ASIO driver. They tend to be better written/supported than WDM these days.