Hi guys.
New here, and I hope you can help me.

I'm living in Norway, and we have 230VAC over here.

I'm running a pedaltrain powered by a Voodoo Lab Pedal Power 2+. My pedal order is Sonic Research Turbo Tuner ST-200; Keeley Electronics Compressor; Xotic Effects AC Booster; Voodoo Lab Sparkle Drive; Voodoo Lab Microvibe; MXR Phase 90; Hilton Electronics Volume; T-Rex Replica and Digitech Hardwire RV-7. Wired up with George L's.
Since there are too few outputs for this setup on the PP2+, some of these pedals are daisied. I run trough a local made 2x10 tube combo, made by an ampwizard that lives here; this guy is amazing, and there's no issue with the amp.

Now, the problem is very hard for me to describe. When things are OK - which is most of the time - this setup sounds terrific.
But from time to time, at different venues, the sound is just "ruined". Even with no effects engaged, the clean sound is ruined somewhere in the chain between the guitar and amp. It sounds distorted in a really weird way. It doesn't matter if I turn on one or more effects, that hum is still marring the sound. As I said, I find it difficult to describe this problem because of the language, but the only way to describe it is that something is inflicting the sound in certain venues.

Sometimes I've found that the problem disappears if I take power from a source that nothing else draws power from, i.e. if I find a solitary outlet at the back of the stage or something.
I have a 4-outlet extension cord reel, so I've also experienced that the problem can occur if someone else takes power from my reel.

What could cause this issue? Could the PP be the problem, and what could be done to get around the problem? It's of course very difficult to do something about the electric system in the different venues I play in.

Thanks a lot.

I believe all your pedals but the Phase 90 are true bypass. This would lead me to believe that the signal problem you encounter even when all pedals are bypassed would most likely be due to a failing audio connection rather than having anything to do with power. If you can test this out the next time it sounds strange, try moving your guitar through each pedal one at a time down the signal chain until the sound returns to normal to find if a cable or pedal is the ultimate cause.

Let us know what you find.