I was about to link the thread describing harsh/grainy vocals when I realized it's yours. Sorry you're not happy with the setup.
Personally, I can't imagine switching to the Pass amplifier is going to be the silver bullet if you're consistently underwhelmed. The Parasound is a good quality amp and assuming the amp and speakers are working properly, those speakers just may not be for you.
You can certainly influence (soften) the characteristics of the sound with interconnects (cd player >amp) and speaker cables. Others may have opinions about brands that can accomplish this, but I can recommend Dueland, available from Parts conneXion. Not ridiculously expensive, and I tamed an almost unlistenable set of horn speakers with them. Not a coloration, but the edge removed.