Mark, in my experance a dedicated line improved matters better than any power conditinor I have used. The general accounts I have read support this also.
A dedicated line sure can't hurt.
I have my ACI Titan II LE subwoofer plugged into a Monster HTS 2000 surge surpressor, and I can't hear any difference in its performance, good or bad (YMMV).
During the warmest months, we get a lot of lightning here in Michigan, and my house has been hit at least twice over the past almost 25 years. Still, I'm sometimes reluctant and very frequently unable to unplug my audio system (or my computer) when weather threatens. Surge surpressors have been very effective for me.
I'm currently considering the installation of a properly-grounded whole-house surge surpressor. Maybe I'll then get dedicated lines for my gear