Newbie with "bright" system

I recently bought a new power amp, and for the first time, my system now hints at recreating a music "venue" rather than playing songs. For this long-time music fanatic, this is incredibly exciting (I now realize I'm hopelessly hooked). Pushing onward, my current system seems "bright" and "harsh," causing listening fatigue at moderate to high listening levels. It also lacks believable bass detail and extension. Looking for low to moderately priced ($300-1500) incremental, high-value upgrades - I suspect cabling and receiver as pre-amp - what to upgrade first?
Arcam Alpha 8SE - CD player
Nakamichi AV-10 as pre/pro
Bryston 4BST
B&W CDM 7SE
Bettercables IC's and biwire speaker cables
"Industrial" metal rack
Any insight/advice welcome. Thanks in advance for input. Mark