Shim, the Pa500 has a pretty decent pair of speakers. I can't see through the cover if the speakers are separated or not (like in the Psr1500) but the arranger has two lateral windows for the air of the low frequencies and I guess those are for the sub woofers. I don't hear any thumping at high volume though I always use my keyboards with external amplification and speakers. I connected the Pa500 line out to the PSR line in to compare both speaker systems with the same sound engine but the sound was too low to compare. The Yamaha sounds crisper and clearer (better to me) and the Pa500 drier ("duller" if the word is correct)