Turntable sounds so much better when...

This is all weird, but...Maybe with the headshell tightened you are getting mechanical vibrations that you may not know about causing distortion. Loosening the headshell may be dealing with some of those vibrations. You may receive even greater nirvana by tightening things up again, and dealing with possible mechanical noise coming from below. This of course is pure speculation.
Kenny

Thanks Kenny, i will continue to dabble and learn more and more Via my Ears..

Dear @vinylholicmusic: " Please help me understand "". Well I think that no one rigth now has the true about.

@ivan_nosnibor post can be true or not at all because the relationship between the TT mat/LP surface/ stylus tip / cantilever/ cartridge body characteristics / headshell / screws-nuts to hold cartridge-headshell / tonearm collar / tonearm arm wand material and damping levels / tonearm bearing / tonearm arm board / etc, etc, is extremely complex to be sure what is happening down there to achieve the kind of sound you are talking about.

As a fact your cartridge/TT/tonearm does not """  that the tighter the connecting fastener that joins two surfaces, the greater the tendency for both material parts to (vibrationally) act as one """, it can't do it for those to many links in that overall chain.

Have I a true explanation ?, no I have not because ( between other things. ) I'm not listening to your system to figure what changes happened and if those changes in reality/true were for the better. Yes, your ears said it but those are your ears.

Try to explain your " fact " is almost imposible because that so complex vibration/resonances generated in between de whole " chain ".

You posted something realy interesting because I used in my system when the tonearm/removable headshell can't be moved of azymuth position:

"""  .and maybe it's allowing the stylus to position itself in the vinyl better! """

that could be because exist no perfect alignment between removable headshell trhough the arm collar. In theory when both are gas tigth connected the alignment is " perfect " with no azymuth deviation.
Now, the extremely critical alignment between the cartridge stylus tip and the LP grooves has to be " perfect " but this never exist in pivoted tonearms not even with LT ones.
A " minute " azymuth change makes differences for the better ( as you experienced. ) or for the worse.
As I said I used that trick in the past.

Anyway the important issue is that you are happy as never before. Good !.

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.

and maybe VTA/SRA.