What commerical audio system tweaks provide sound quality improvement??


If you look in any audio catalogue, whether Music Direct or Audio Advisor, there are usually several pages of  system tweaks.

What  tweaks in your opinion, work and actually provide real audible improvement??

Thank you , SJ

sunnyjim
If you are using a computer to a DAC for digital, try a USB Disruptor and the accompanying USB cable, only around $170 for both. Sounds better than my $500 USB cable. Lower noise floor and can listen to for much longer periods without fatigue. Also sounds better than the Uptone Regen and much much better than an AQ Jitterbug. 
Ok, so let me ask the obvious stupid question. I know that resistance in electricity is big. The less resistance the better more usable current. I have 14g ordinary radio shack speaker wire run to all my klipsch surrounds and rear surrounds and my mirage os3 fs towers and mirage os center. Would I REALLY notice a difference upgrading those cables? 14g shouldn't have too much resistance coming from an Emotiva xpa3 and xpa5 right? But i do have custom badass interconnects