If you want to try looking for a voltage problem, you could get a simple multi-meter, stick the probes into the outlet and then watch it while someone else fiddles with other devices. You'll watch the AC voltage on the meter while someone else flips stuff on and off, and you might see a voltage drop.
The only way that voltage (especially through a power conditioner) should be a problem is if it's going VERY low. The power conditioner is nice, but it's not able to make up for insane voltage drops.
If you really believe that a voltage drop is the problem (as opposed to RF noise or something), get a real on-line UPS - Note the words 'on-line' there, that's important. What you want is a UPS that provides constant power in the face of brown-outs, black-outs, etc. The idea is to find one that's ALWAYS outputting from it's power conditioner and which has zero cut-over time in the event of power fail. Some cheaper UPS don't do that - instead they switch the source AFTER the power fails. That switch over can take hundreds of milliseconds. That's OK for some things, but for your purposes, it's not useful.
One other thing to check is whether the circuit your receiver is on is heavily loaded. If you are near the limit of the circuit (in other words, if you are close to tripping the breaker), then the breaker's activity when it's near tripping could be doing something funny to the voltages. If you suspect this, then you should try to get as much as possible off that circuit.
A kill-a-watt can be used to measure the load added by plug-in devices.