So, the house I live in does acoustic shows 2-3 times a month in the basement...
The basement is poured concrete, and roughly 10 feet across by 20 deep, with stairs running down one side. Bands set up between the stairs and the opposite wall (let me know if this is making sense). The back wall has a couch and some various other stuff (water heater etc) so slapback hasn't really been an issue. there are wooden ceiling beams every foot or so that I can mount mics to, but here's what I've got at my disposal:
-SM58 (this is generally used for micing vocals, which go through a small PA)
-unknown condenser, looks like an SM57 but the casing is grey
-CA-11 (cardiod)
-SP-BMC-2 (omni)
-Carvin SM162 mixer (16 channel)
-Edirol R-09
-numerous laptops
We did a show last night with the CA-11 and a Shure KMS32 that one of the touring acts showed up with, CA-11s on a ceiling beam into the R-09, Shure into the console and then to a Laptop from there. Sound like a good mic config? I'd be glad to post photos or more precise measurements if anyone would like
I looked up your console and this is what I'd do. 2 things that you'll have to do for my idea...
1. PA system has to be run in MONO
2. You'll have to mix on the fly with headphones
...neither are terrible especially for acoustic acts in basements, in my opinion.
The Singer's vocal mic and maybe a DI for his guitar are fed into console channels. Set levels and Pan those hard left. Now, run whichever recording mics you choose into other console channels. Use the console's preamps to set levels, and pan those hard right. Your PA amps will be fed from the Left Main output of the console. The Right Main output is not used. This takes care of the PA system.
Your recording feed is going to be stereo and will be fed from the EFX 1 and 2 sends on the console. efx1 is Record Left and efx2 is Record Right. If you're recording to an R-09, you'll have to get cables/adapters to adapt 2 1/4" TS to 1/8" TRS. Monitor on headphones and create a nice blend of the vocal mic, guitar DI, and your stereo room mics. Make sure you're sending audience L record mic to efx1 only and audience R record mic to efx2 only! These are your "quasi pan pots." Singer's guitar and vocal can usually be right up the middle, so equal level on both efx knobs for those channels.
Make sense? I tried to be brief. Make your rig's footprint small and don't lose gear to a house party. It's happened to me more times than I'd like...
You can always record to two separate decks and do the matrix later, but this is much easier and probably will sound just as good as a matrix. As long as the delay between PA and audience mics is not too noticeable, this approach will work well. Just mix it on the fly, and be done with it.