Not wanting to lug yer ASR-10 up and down stairs is a good enough reason for me, god knows i know just how heavy that beast is

As for feedback, the reason why you got feedback with your guitar was because the audio signal from the speakers was going through your pick up an infinite number of times. This can only happen w/ your ASR if you plug a mic into the audio input and have the audio tracks turned on.

As for blowing your speakers, as long as you keep your volume at a reasonable level, you have nothing to worry about. If you want to exercise caution, turn the volume all the way down on the stereo when you turn it on and have the ASR already plugged in before you turn it on... then you can hit a key and then raise the volume to a reasonable level...

i understand you wanting an amp, and i say go for it. i'm not trying to dissuade you. Maybe one day you'll be in a situation where all you have is a stereo system and hopefully my tips will help you out if that day ever comes ;-)