new at this...which amp?

I have B&W htm1 center, cdn nt9 front, cdm nt7 rear with Adcom 7500 150 by 5 amp and Adcom pre amp. The mids and highs are harsh beyond half volume. Speaker cables are the good stuff, but interconnects are Radio Shack's best sheilded cable. I have been told here that while interconnects could be the problem it is more likely lack of power. Would Adcom 7805 300 by 5 be a reasonable choice for a new amp? Is there a better choice for around 2500.00? If the 7805 is not enough I am considering bi amp with the 7500 and 7805 as the final solution. If so, would the more powerful amp go on the bottom end? Your comments are greatly appreciated.