Aah... yes, I'm certain the THR10 won't really cope, on its own, with anything jam-wise other than a quiet "living-room" session. You could drown-out/p1ss-off the acoustic guitar player, but you couldn't do a lot more damage than that (it is loud enough to annoy sensitive neighbours if you go for it, though).
Having said that - it has replaced (for the moment) all my other kit as my go-to recording amp. I was stunned...
I use the headphone out, straight into the line-in on the mixing desk. At first it was a bit fizzy for my liking, if you have the volume at head-phone levels, that is... (I wouldn't recommend it as a headphone practice amp on its own, but in most situations I can get the speakers quiet enough to not need headphones when practicing - it passes the "wife is on the other sofa watching the TV" test, I'm playing through the THR speakers, getting a tone I can relate to, and she doesn't turn up the TV or complain...).
But anyway, using the headphone out as "line out", if you crank the THR10 volume up to full, then things get pretty darn gorgeous... Obviously, I'm listening to this through the same headphones and monitors that I used to listen to my Vox Tonelab, POD XT, and plug-in stuff (back when I had a computer anywhere near my recording kit!). For me, it knocks everything else out of the park - and, of course, re-inforced like this, it could gig just as easily as any POD/wotever solution.
It has actually stopped me using my little Laney CUB12 that I loved so much. To get the same "valve-amp" kick as I do out of the THR10 (at watching TV levels), I have to crank the CUB12 to "Andrew is uncomfortable" levels (regardless of what the missus or the neighbours might be thinking!!). And cranking the headphone out signal, you can get that same sound out to another device to do what you will with it.
btw - for anyone wondering, the THR does have USB, I use it as laptop speakers. I have tried using it as a recording interface once - and it does the job... but I don't do my recording on a PC/DAW, so I don't have much use for that side of things. If I did, I'd never have thought to try the headphone out route!...