priorities-better cables or power conditioning?

Current system; denon 2900, BAT vk30 pre, MF A324 DAC, Odyssey stratos w/cap upgrade and Martin Logan Request for 2 channel. Yamaha rxv 2095/mitsubishi 64" HDTV, paradigm cc350 and monitors for HT. Bat pre p/thru for HT so Odyssey and MLs for front L/R in HT mode. Only conditioning is Monster hts 2000. Monster cables except MIT biwire on logans. All on same dedicated but not heavy duty AC line. Large,well damped room in basement-fully carpeted. Some stridency on higher volumes with music and HDTV via comcast not as sharp as should be, esp sports. Looking for input on best bang for buck-upgrading P/Cs,interconnects to Signal products, or BPT 2+ conditioner, or running separate 20 amp circuit for amp w/hubbell outlets. Audio is 1st priority.