Your most indispensable "tweak"?

For less than $500, the Akiko Audio Harmonizer Unit is the best tweak that I have ever experienced. It transformed my system above and beyond what I hoped it could do. It is also the most straightforward tweak to install because it's connected to the IEC ground in my power conditioner. 

Vocals sounded 3-dimensional before adding the Harmonizer Unit. After adding the Harmonizer, the music sounded REAL! It gave me goosebumps. The noise floor vanished, and the soundstage layering is now phenomenal.

@puffball08 In what amp did you perform those mods?

@toolbox149 The Schroeder Method is on my to do list. It will be very disappointing if it doesn’t work out in my system.