Chas,
Have you considered trying two Bose L1's or Compacts?
The reason I'm going for the L1's is that I've used them in the past, and I am familiar with their performance.
All we can do is rely on what we hear, and what we
like to hear...if I'm playing a system that makes my keyboard sound at it's best (which happens to be stereo for Tyros3 and PSR-S-series) then I'm going to enjoy the playing experience much more, and also pass this vibe on to my audience.
It's no more difficult to understand than the difference between playing an instrument we like, and that seems to suit our style, and one that doesn't quite feel right.
And, as I always say, we are ultimately
playing the speaker. It is the last link...like the vibrating string and soundboard of a violin.
It reminds me of the difference between a real Leslie, and a simulator...one is actually animated and moving air...one isn't.
The Bose in stereo(as most stereo systems would do) gives more animation to the instrument's sound (especially an arranger) and
spreads this effect to a much wider degree than a conventional system.
Some are content to use only what is needed ("that's good enough")...others want to their sound at the best it can be,
even though they might even be the only ones that notice....some fall somewhere in between.
So, Chas, what have
you learned? Do you now have more interest in trying out two Bose systems, to find out what
your ears tell you?
Surely they are the final answer.

Ian the Curious
[This message has been edited by ianmcnll (edited 10-20-2009).]