Right, do let me know if I stray into the realms of utter bullshit here as this stuff throws me quite often.
In my live setup I'm running a guitar through a laptop for effects. (I know the reaction here in some cases might be 'buy some pedals you idiot,' but I'm working with what I've got for the time being) It sounds great recording through a DAW, less so chained through an amp. Even with amp modelling turned off in the software and going through the clean channel on the amp, I have a bit of trouble controlling feedback and hiss. My external soundcard is generally great so I don't think the problem lies there, unless it's something I'm doing wrong with the volume settings in the chain.
But anyway, I've also got a hankering for incorporating some sounds generated by other apps on the laptop. I can route these through the second output on the soundcard so can externally mix them separately, but suspect these would sound even more rubbish through the amp.
So next time I might try putting both outputs (guitar and laptop-generated audio) through the PA. Are there any pitfalls here that I should look out for? I'm guessing that I should leave amp modelling on in this case, but how well does this work? Any advice appreciated, anyway.