Tweaks that work? (yes very subjective topic)

For me the cheapest tweak was to remove the speaker grills on my Vienna Acoustics Mozart Grand SE’s.  Most speakers sound better with grills removed in my opinion.  Nothing cheaper than free.

I have used and have extra tubes of Total contact also known as perfect path and it works on all cables in your system . It’s not cheap but it works great and if someone wants to buy some I have 5 tubes for sale

Tweaks that worked for me were. 1) dedicated line of 20A on separate phase 2) star wired distribution block. 3) high end receptables and iec connectors Oyaide C004 4) neotech power cables 5) master base under all my equipment 5) audioquest sorbothane pieces (cut to size) under interconnects, low level cabling 6) cable dressing 7) hifi tuning fuses 8) diffusors behind my listening seat 9) JSSG 360 shielding (cable tweak from computer audiophile website) 10) friwo medical smps with ultra low leakage currents for modem and non audiophile equipment 11) linear psu’s for audiophile equipment. 12) hqplayer and fidilizer for htpc 13) star quad geometry for DC cabling. 13) smoke weed 14) play music loud 😁

I'm using a tweak that is definitely not snake oil;  High Fidelity MC-0.5 power conditioner modules. They plug into the duplex receptacles, I'm using three modules. They have added more detail with a smoother presentation, lower noise floor, and holographic sonics.
There is now a MC-0.5 Helix Plus available with increased benefits.

My favorite tweak lately is called the Mystery Tweak. There is one for CDs and one for cassettes. It involves stiffening them and damping them, thereby reducing distortion. I would very much like to say what the Mystery Tweak involves but then it wouldn’t be a mystery any more, would it?