Dumb question? - no such thing (well, actually the dumbest question is the one that people are afraid to ask...)
Two parts to the answer:
Most people use a separate mixer (or separate pre-amps) with the 1680 as Roland is not renowned for having decent pre-amps. Depends on how many channels you're looking to record. the 1680 will record 8 at a time. You could do worse than get a Mackie 1202 VLZ-Pro (or two) - they're quite inexpensive, and provide reasonable pre-amps without breaking the bank.
You don't need a separate mixer to be able to pan in real-time with a VS-1680. Usually you record each mono channel to a separate (mono) track, so the question of "panning" is a moot point. However if you're recording to a pair of tracks (ie. mixing all your inputs to a stereo-pair (of tracks)), then the panning is important, and yes, it can be done in real-time.
I hope this answers your question.
- Wil