My house was built in 1926 (!) and has gobs of the old 'knob and tube' wiring that they used in that era. When I moved in, I just plugged in my amplifiers, the biggest one of which is a 1000 watt stereo amp I use for my subwoofers, to the existing outlets. Everything worked pretty well with no outright problems. The only thing I did was replace the recepticle on the wall because it was old, and it's connectors were weak. I have since built a dedicated room with all new wiring, but things don't work any 'better' than they did with the old 1926 wiring.

One thing you should consider is that the power requirements of your power amplifier are remarkably light for most of your listening. The instances when anything near full power is needed are brief, for that obligatory explosion and car chase. I think you might want to replace the recepticles you plug everything into, but you can probably delay a more extensive re-wiring job.

A "1600 watt" hair dryer consumes basically as much power as a home theater power amp at full tilt. If your hair dryer works OK, your power amps probably will too.