Hi Leigh, aka sz member:(jazzhooves), many thanks for your review, especially realizing you initially inquired about the Bose L1 on this earlier thread.

From your review, I surmise you were utilizing 'two' L1 units for full stereo, not just one. Did you get a chance to test it out with your Tyros 4 going out to only 'one' L1 unit?

If so, did you detect any sound degradation (aka: stereo phase cancellation') playing Tyros 4 stereo sampled voices, such as the 'concert grand' piano?

As Ian mentioned, though two L1's together in stereo sound awesome, I too don't think a single L1 unit alone to be sound satisfactory with Yamaha keyboard 'stereo sampled' voices.