Is it possible a 20 amp outlet can make a big difference in SQ?

I doubt changing the amp rating of the outlet, but keeping all other things the same (brand, line,, etc) would matter by itself.

There’s two things I immediately think about:

• All 15A outlets in the US are rated to be on 20A circuits. To do that they have to have the internal conductors as thick as a 20A socket.
• Some manufacturers improve economy of scale by making the 15A and 20A outlets identical behind the faceplate. Same conductors, wipers and plastics.

If you aren’t going to re-use that 15A outlet may be fun to take a hand grinder/multitool (i.e. Dremel) to the face and remove it to see if it doesn’t have the T shaped wipers of the 20A units.

The reason for the multi-rating is areas like a kitchen, where you may have multiple appliances going. They may each be under 15A, but by using a 20A circuit you can minimize breaker tripping.

The 20A plugs are usually reserved for commercial settings and 1-2 outlet circuits where the electrician wants to indicate "this is where you can plug in the hotel vacuum. "

@lak Note you tagged a different AG member...anyway, I don't know what gauge the wiring is. I can only assume the house is wired to code - the majority of the breakers are 20 amp. 

@erik_squires this was my understanding but I thought the 20 amp outlet may allow a bit more current. Maybe, maybe not.

Not going to tear the 15 amp apart - at this point I'm happy that the new outlet is properly installed maybe the old one was not - and after a lot more listening, for sure there is major improvement in SQ.  

OP:

Also depends on the original installation and age. If you cleaned the terminals with fine grit sand paper before re-installation and tightened everything properly it is possible the better sound comes from elbow-grease rather than hardware.

By the way, I found the Leviton 90 degree, hospital grade plugs to be really tight, and the 90 degree feature super convenient for saving space around the sockets:

https://amzn.to/3XUV7e6

My outlets are in the corner behind my bass traps so this type of plug saved me several inches of floor space.

Best,

Erik "cryo"

macg19,

Sorry I meant to tag you. 
I wanted to be certain that the gauge wire in your rented home is correct for 20 amp circuit breakers.

Found a video showing what I meant about 15 and 20A outlets sometimes being identical:

https://www.youtube.com/watch?v=6jUa_HbUeoE