Jim (Pro), I'm pretty certain the Yamaha piano 'stereo to mono' conversion phase problem has nothing to do specifically with the Bose PAS, but that the identical problem occurs when going from a Yamaha keyboard's stereo sampled acoustic piano sound to ANY single 'mono' output speaker. I hear (on the PAS) the identical 'phase cancellation' problem when going from my Tyros to one single EV SxA100 speaker as well.

On the other hand, re the PAS, even if the phase problem were corrected, though I was impressed with the 'overall' PAS sound, especially the clarity of the mid range, the mid 'low' frequencies are strangely lacking, making the low notes sound thumpy (accentuated) yet lacking pitch clarity. I personally find my EV SxA100's to have a smoother natural (unhyped) sounding frequency respond from top to bottom.

I'm intrigued by the possible prospect that the "IBP Junior Analog Phase Alignment Tool" might work in correcting the phase cancellation problem, though $375 sounds a bit pricey. Still, if it actually worked, I'd be willing to fork out the cash so I could send my Tyros' stereo audio output to a single EV SxA100 speaker when desired. Anyone actually tested the IBP Junior Analog Phase Alignment Tool out? I'd really appreciate hearing feedback from people who've actually tested this out in correcting Yamaha keyboard stereo sound output to a single mono speaker. If it works, then this could be the unit we've been looking for.

Scott