Best Tweak???

A dry red really helps the listening experience. Seriously though, I think there are 3 must tweaks. Room treatment[room dependent of course], vibration and isolation treatments and power line treatments. To pick just one is hard as they all three combine but a huge trick was taking the spikes off the target stand and sitting it on large halved superballs. Friends visiting from the city laughted when they saw it because they also had done the very same thing. We both have "bouncy or live" wood floors. This has to be my cheapest tweak and may or may not work well for you. Remember, very heavy weights could split the superballs[I'm guessing], so do be careful. Cheers.

A puff of weed.

I second Docsavage ZERO recommendation, but it is system dependent. My previous speakers (N.E.A.R. 50Me II) benefited greatly from the ZERO's. I inserted one pair and was very happy with the improvement to the bass. I then tried a different configuration and was happy with the refinement, but lost the bass benefit. I then bi-wired with two pairs of ZERO's and the improvement exceeded my expectations by a mile and a half. My current speakers (Köchel K-300) don't benefit from ZERO's at all.

Q-tips and Murine Earwax removal system. Major improvements in all ranges of frequency and detail.

Halo tube dampners, Walker SST, any record cleaning machine, good ac wall recepticles. For my system the best tweek was a Rat Shack remote extender, it allows me to keep all my tube equipment behind closed doors while still using my remotes controls.