Your most indispensable "tweak"?


Trying to narrow my possibilities down... 
redwoodaudio
Dedicated 20 amp circuit  with an audioquest nrg power outlet and furman power conditioner. 
@redwoodaudio 
There is a big thread on them here in the forum. 
Can you link to this thread please?  Search does nor find it. 

Best of all:

2 dedicated audio lines with hospital grade outlets and 10 gauge wire. Was not expecting it to make a big difference...and it wasn't...but it wasn't a small difference either. It was a solid upgrade.

I had ordered a new tube amp when the lines were put in and I almost wanted to cancel.
I had a Carver with great high end but weak bass...and the bass was now sublime...overall sound was more focused.