After pondering the options for a while I decided to try a mixer rather than the audio interface. Although a really cheap mixer probably would have been adequate for my current needs I sprang for something a little better and picked up one that has USB. It's the Yamaha MG 10Xu. Undoubtedly overkill for my needs, but what the heck, it's Xmas. I'd welcome any comments on the appropriateness of my choice. Thanks again to everyone who has weighed in on this topic.

Hopefully not to overburden you folks, but my next question on a related, but different topic, involves the MIDI/Audio Drivers settings in BiaB, and whether or not I can improve the sound quality I'm getting from BiaB by somehow utilizing my Roland RD as an external MIDI device. I'll post a new question regarding this topic so it doesn't get all intertwined in this thread. Thanks!