Trusted
sidefx: Hmmm, a 12V\1A adaptor "works" but doesn't seem to drive the sub-woofer properly - it just makes annoying popping sounds when turned up a bit (even still relatively low - less than half full volume). And of course the speakers output a much lower volume.
The main issue would be not enough current to drive the bass speaker, but it does sound like 12V might be a bit low so sorry don't think I can help you. That 15V option sounds like it should be sufficient.
I wonder if it was designed for an unregulated linear power adapter and then when they were forced to energy efficient power adapters it worked out to 17V. Or maybe they were just not concerned about cost (to source an unusual voltage power adapter).
... 
