PinkStrat, I also have a VS workstation -- an old-school VS880 -- which is great for on-location recording. It only gives me 4 simultaneous analog ins, but if I get
a Flying Cow converter or maybe one of those DBX thingies, that would give me 2 more additional inputs. I don't have an 840, but here's how I would set up my VS to take in 2 digital ins:
Let's say you're recording 2 tracks simultaneously on tracks 1 and 2.
1. Press SHIFT + Ch. Edit 1 for track 1.
2. Use the dial to select your input. Because my 880 supports 2 digitial channels, I will rotate the dial until I get the choice "DIGITAL-L".
3. Pan your input for Track 1 all the way to the left.
4. Press Ch. Edit button on track 2 (will give you the last edit parameter screen you were in, the Input/Buss one you last selected for track 1 in step 1).
5. Rotate the dial and select "DIGITAL-R."
6. Pan track 2 input all the way to the right.
If your 840 supports two channel input, it will let you select each channel as either L or R.
I hope this helps and translates to your VS 840.
As for preamps, right now I have
a BlueTube, which is on the way out, and a single-channel Dan Alexander Audio racked
Neve 1073, which sounds awesome. As mentioned previously, it's not about what pre "works" well with Roland. You can get any pre that has the sound you want and you'll get that sound if you keep the input sensivity knob on VS in all the way down.
Oh, the other thing with these VS systems is you want to record into them in a mode that doesn't use that RDAC, roland's internal data compression -- otherwise it will have this undefinable "flat" sound. For me, that's MAS mode. I don't know what it is on higher-bit, newer machines (MTPro?). You'll get less workable tracks this way, but you can now bounce with impunity (no degradation, just keep your originals on another V-track), and I've begun using S/PDIF and MTC to dump down tracks into Pro Tools Free. We'll see how that experiment goes ...
I honestly think I'm going to either get a Digi 001 Factory or Delta 1010 card and some other software for home multitracking, but I'll hold onto the VS because it's great for on-location recording, it's easy to use (I'm used to the interface), and it NEVER crashes.
If you have any other concerns you think I might be able to help with, PM me.