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.