Rank the tweaks, geeks!

While upgrading componets ( external and internal ) generally give you better or more pleasing sound . Two tweeks that suprised me were replacing the weight on my Rega RB300 tonearm to an Expressimo that lowered the center of weight and replacing a PS Audio power outlet to
an AudioQuest NRG edison ( does this count as " electrical " ? ) .
One I tried didn't like were tube dampers .

My list doesn't exactly follow the Op's list (my apologies, but then, I never have followed the rules) but the improvement I experienced when each was implemented was significant enough to warrant a mention.

Most important tweak in my opinion, though probably not an actual tweak is dealing with room acoustics. I dealt with mine electronically instead of acoustically because of cost, floor space and WAF. I do plan to explore acoustic options in the future.

The next biggest improvement was when I switched to fully balanced operation. The improvement in tone, dynamics and system noise was completely unexpected.

This doesn't fall into the tweak category either but the improvement was significant enough that I feel it needs to be mentioned, adding an active crossover between subs and mains. The difference in clarity and tightness in the low end was rather eye opening

Time aligning the subs and mains added even more clarity, space between instruments and improved imaging.

My last tweak is actually on the Op's list, component isolation. I haven't done extensive isolation and because of my penchant for loud, bass driven music the isolation platform under my TT is more of a necessity than a tweak. Other components I have used minimal isolation on so far are my subs and amps. I also have plans to explore isolation under my other components and improve the isolation under the subs and amps. 

Well dealing with room acoustics is all about tweaking starting with choice of speakers and then where to put them exactly and whatever else follows from there to get a handle on things initially. I would agree to put that one on top of the list. Right up there with clean ears.

Great thread.
In ranked order:
1. Speaker Cable. Townshend F1 Fractal and to a lesser extent HFC CT1-E cable were so far above anything else.
2. Power cord to DAC. Not any power cord. Only the Shunyata Alpha EF did the business. Others had minimal effects.
3. Speaker Isolation. On my B&W 804D Gaia feet were transformational. With my Boenicke speakers they have a bespoke ’swingbase’ which isolates the speaker in a similar fashion.
4. Adding a CAD GC1 and 3 - a grounding device, one for signal ground, the other for electrical.
5. Rack isolation using Townshend Seismic corners. These isolate the whole rack, making it ’float’, and mean individual component isolation is not necessary.
6. Power cord for my integrated amp. Again the Shunyata made the difference, others much less so.
7. Interconnects. Actually only one - all sounded identical except Townshend F1 Fractal, same as my speaker wire. There is something magical about the F1 loom.
8. Adding a Cisco switch between the router and bridge.
9. USB cable connecting the Roon endpoint to the DAC.
10. Changing from ethernet cable to an optical network (definitely not WiFi)
11. The type of Ethernet cable between optical switch and roon endpoint cable
12. Power cable to the active bass subs in my speakers.

Things that made no difference for me:
- cable risers
- the type of cable between my amp (pre-out) and the active bass units in the speakers
- the Ethernet cables from the router to the first switch

terry9++ just wish I had more '05 red Burgs

speaker isolation: Nobsound weight bearing limit is 80lb per quad. What springs for 140 lb. speakers? 8 Nobs under each speaker feels a little fussy.