Your most indispensable "tweak"?


Trying to narrow my possibilities down... 
redwoodaudio

I don't know what constitutes a "tweak", but:

1- Room acoustical treatment.

2- Loudspeaker and subwoofer placement within the room.

3- LP cleaning.

+ 1bdp and to properly integrate the subwoofer to include the right crossover point and gain.
Power cables, interconnects and speaker cables.  Without them, I can’t get my system to work.