Hmm, my Tascam US-428 seems to have died.
It lights up. It controls MIDI gear with no problem. My MacBook Pro recognizes it, as do many programs (Logic, Live). Yet, I get no audio. I've tried headphones and speakers, all to no avail. I loaded in new drivers, and went through a variety of settings.
I've even tried running audio into it directly (from my Clavinova), also with no results. I think the audio card on it must be dead.
Tascam says the model is discontinued, and replaced with the US-144mkII. Okay, that's a nice device, but it's hardly a replacement. The US-428 has 8 faders, which makes it look more like a mixer. The US-144mkII has 4 inputs (like the 428) but two dials control the input volumes. And, it looks like you switch between "Line In" (guitar/keyboard - 1/4" jack) and XLR input. So really, it appears to be a two channel input. It's pretty cheap (Sweetwater has it listed at $149), but nowhere nearly as cool as the 428.