Ok, WHERE can I purchase the model 'SxZB' Tote bags for the EV SxA100's? Also, how much do they cost?

Also, currently, with the SxA100's connected directly to my Yamaha PSR2000, I seem to be getting plenty of volume (for small-medium venues) without needing to add an external pre amp/mixer.

I'm now wondering how much less (or more?) volume I can expect if the SxA100's are connected directly to a Ketron XD9 keyboard or Yamha Tyros keyboard, compared to the volume I'm getting from the SxA100's connected directly to my Yamaha PSR2000.

Thanks in advance,

- Scott