Funnily enough, a long while back I sent a Tripp Lite Isobar in to Tom's Hardware for a teardown and testing. The final page with the testing is here:
The iconic Tripp-Lite isobar falls under the knife in today's power strip tear-down. Is this unit as well-built as its heritage suggests?
www.tomshardware.com
While we can't know if the construction is the same nowadays, it seems likely it's similar. Long story short, you'd want to plug any noise sensitive devices into the first bank of plugs, where the isolation is effective. Other banks, particularly bank four, can actually have noise amplified to the point of seriously distorting the waveform, if you have something very noisy plugged in to the same strip.
Of course, to actually have any effect on electronics like an amp, you'd need a seriously messed up waveform and/or excess voltage. And you wouldn't likely be looking at subtle sound quality issues. Most likely, absent some very strange situation, the effect of using an Isobar (or any other surge protector) will be nil.