Is there any way that I could use these components together as a music performance PA system ? The sound from my Sony audio system is just amazing and I'm wondering why I can't use this instead of buying a new PA system. I was also considering the Bose L1 but it's pricey. Why wouldn't my high-end Sony system compete with the output of the Bose L1 ?

[] Prerecorded music is usually modified and its dynamic range limited; a live performer often "hits the ceiling" with output spikes in dynamic content (unless there's a compressor / limiter on the instrument and/or singer)
[] Live performance audio systems are designed for playing loud (and dealing with the waste heat generated - heavy duty wiring, cooling fans, circuit breakers, output limiters, etc)
[] Live performance audio systems are not necessarily "high fidelity", trading accuracy for efficiency (SPL per Watt consumed)
[] Performance grade systems are more durable and idiot tolerant (not idiot proof)

Home audio systems are designed for a different set of conditions and would not fare well in "live" use.