uh, many questions and i just switched over to having a beer after a long day ;-) so forgive me any imprecisions, please :)
After long mixer search (had a discussion with Smithy on this forum last year, there is also a thread somewhere) and the obvious choice of analog (cheaper, more headroom, no double adc/dac conversion) vs digital (total recall, dac/adc conversions only once if you have an integrated firewire interface and if you control everything from your daw afterwards) and my daily routine use of computers (sometimes being fed up with them), i decided to go completely analog, old-school :) - no need for a pc for jamming. But, ofc. sometimes you want to record things, so this is the (cheap) setup:
- old 2003 1604 vlz mackie, which offers 4 +2 busses, which are recorded (see below)
- 8x8 sound interface (m-audio fasttrack ultra), 96khz-capable. I use this to record my digital synth (2 channels) and the 6 busses from the mackie. I currently use one bus pair as a "dry" bus - all synths, one bus pair as a "wet" bus (fx returns) and the master mix out bus pair for recording "live sessions". The mackie allows dynamic assignment of instruments to all busses, so you switch around from wet/dry/main out recording to recording any instruments, if you choose, you can push a few buttons and record six individual (mono) instruments on six channels, or three stereo instruments, which is enough for my recording requirements.
Going out of the pc, is a digital line to a digital synth (sampling) and two (stereo) channels assigned to the mixer and using two of its 16 channels. Using the mixer fx-sends potentiometers, I can use any pc-based instrument (vst) and send it through old-school fx units (e.g. delay or distortion unit) and record it again.
You need 4 pairs of nodes to setup 4 full-blown instruments (input and output to pc) continuously, but consider if you need it continously.
I did setup only a pair for the machinedrum and a pair for the roland synth. When i need rutgers mb6582 manager, i create another routing temporarily.
The mbseq busses are used internally - i have not investigated this further - for nice effects like self-altering tracks. TK has written a lot more in the handbook, which i need to read again ;-) - for your request it is sufficient for you to connect IN1..X to USB1..X and vice versa.
Have a nice evening!
Peter