Need Help: What In My Home Electric System Killed the Sound?

Could really use some troubleshooting from you electric experts out there, of which I certainly am not one.  House is in rural western Maine.  My electrician (licensed and very experienced, but not in audiophile context) is running a dedicated line to the 2-channel rig.  He installed the new line up to the outlet, but didn't complete yet (we're waiting for delivery on the outlet), so the new line is temporarily capped off at the wall.  In the meantime, elsewhere in the house, he changed a broken recessed light socket and changed the related wiring to that light.  Those are the only two changes to the electric I am aware of.   The 2-channel system remains plugged into the same outlet we've been using for years (until the dedicated line is in).  This weekend, the life is gone fro the system.  For example, volume at "25" on the pre-amp would normally be quite loud, but now it needs to be turned up to 40 to get the same loudness.  Regardless, dynamics are gone, tempo is a tiny bit slow and has lost toe tapping, and vocals moved from near field to way back in the mix.   Nothing was changed in the system (Rega Saturn CDP; McIntosh C52; McIntosh 452; and Polk SDA 1.2 TL (heavily modded)).   Any thoughts on what might have cause these symptoms?  Electrician can't pinpoint anything.  Any input appreciated.  
If there is no obvious change to your system itself, I would suggest ruling out electrical service by temporary use ("in-home evaluation") of a power regenerator along the lines of PS Audio Power Plants or Torus Power. (Right now, PS Audio has a great deal on their large units.) This will take voltage level, noise etc out of the equation. Even if it's not the problem right now, chances are excellent that this kind of device will make a substantial positive difference, regardless.
That level of change from AC is  quite a reach for MAC stuff, it's designed well. I know as I design high-end electronics along with all my friends out this way (Paul McGowen, Jeff Rowland, etc).. AC meter - maybe but doubtful - an AC re-generator like Paul's unit (PS Audio Power Plant) is a super-quick way to rule out 99% of AC issues as well as improve your system anyway. All systems should have some form of AC power conditioning.. 

Something MUST have failed coincidentally or have gotten mis-wired.

Never ignore the majority of problems with high end audio systems - the human oops factor!
Probably not the AC Electrical supply.  Most likely a component partial failure (only guesses here but maybe in a power supply issue).  If possible try substations for components to find the culprit. If you have not changed anything in your setup from your previously "good" sound then that can be ruled-out.  Best of Luck.
cousinbillyl "Watts (and therefore KiloWatts) are amps x's voltage. Since motors (fridge compressor and furnace fan motors as examples) work on current, this current draw remains constant, but the voltage is higher, so you use more 'watts'. Hydro company makes more money, blah blah blah."

Sorry, but you don't know what you're talking about. Every compressor is specified by its manufacturer at a specific voltage and amperage rating. The voltage your utility is providing is well within the nominal 123VAC that is standard in North America. Devices such as compressors will overheat at low voltages, leading to unnecessary early failure.

Put an outlet on that new line, just borrow one from another place. But I'm betting it's in the equipment. Does the 452 have gain attenuators? Clean all connections. Switch out the source?