P.Animal-
If the reefer is off or unplugged, any receptacle downstream doesn't know it exists, since residential branch circuit receptacle outlets are wired in parallel. Individual receptacle outlets are "tapped" off of the main wiring runs, so that removal of any individual receptacle will not kill any other recptacle.
So I'd experiment (in the interest of science ) and unplug the reefer and have a listening session. Then I'd remove the Acme, wirenut the wire ends for safety, and have another listening session.
Possibly the original installation - if it was anything like my place - was 25 yr old back-wired, bottom-of-the-line residential/builder grade, sub $1.00 receptacles where you could blow on a plug and it would fall out, the contact pressure was so low. In that case, you have some high impedance values on the hot, ground and neutral connections that may have contributed to audible and inaudible noise when the reefer was running. And that would also contribute a voltage drop to downstream outlets. Possibly what you're hearing is the result of another plus volt or three AC to your equipment, so it may be a wee bit louder than before. Note that most audio equipment is spec'ed with a AC spread of like 95-130 VAC, but who knows how it sounds at different levels within that spread?
When I purchased my home 2 years ago, I undertook the replacement of every receptacle and wall switch with Leviton Commercial grade devices. Part of this operation included cleaning & ProGold'ing the wire ends and receptacle terminals before reinstalling. No surprise that the screw terminals on new high quality receptacles are grungy... Devices were side-wired and torqued to manufacturer specs (HIGHLY critical.)
For cleaning copper wire, ketchup (aka catsup) works in a pinch. I used Wright's Brass Polish, since it's water based, and in conversation with the factory they confirmed that it doesn't contain any anti-tarnish agents (i.e. oils.)
I then disassembled the interior branch circuit panelboard and cleaned all wire ends, the hot and neutral busses, the ground wire ends, and ProGold'd everything. Aluminum feeders to the range and clothes dryer were de-greased, sanded, and treated with anti-oxidation compound.
At the service panel, I repeated the same operation on the feeders to the interior panelboard. These also were aluminum conductors, and they need special care and feeding.
I believe that one need to approach home power on an entire system basis, from the utility connection on down. As a result of what I did above, when I replaced my system receptacles with the FIM's, I only noticed a slight (very slight) increase in midrange clarity.
I'd sure like to hear the results of the experiments mentioned in paragraph 2 above...
