Rega Planar 3 : Heavily upgraded yet produces a sound that I don't like


I have the Rega Planar 3 turntable for 30 years now. It had an original everything including a 100$ nottingham analogue cartridge/stylus.
Sound was not bad but pretty basic....
A few years ago I started upgrading it. I did all the upgrades together and the result is... not good. The sound is very accurate but it is too bright, there is almost no Bass and drums have no attack whatsoever.
I can't eliminate where the problem is because all upgrades are irreversible.
I know that the Ortofon Rondo Red has a very bright sound but still...

 

Here is a list of the upgrades :

1. ISOkinetik ISOvert Rega Tonearm VTA Adjustment Kit

https://www.analogueseduction.net/isokinetik-upgrades-and-parts/isokinetik-isovert-rega-tonearm-vta-adjustment-kit.html

 

2. Cardas Litz purple phono cable

 

3. ISOkinetik Tonearm Low CG weight

https://www.analogueseduction.net/isokinetik-upgrades-and-parts/isokinetik-isoweight.html

 

4. Ortofon Rondo Red Cartridge/stylus

 

5 Linn Linto phono pre amp (an old but outstanding piece which has a cult following).


6. I use Rega Elicit Apmplifer


triskadecaphobic
A quick update..
The local Rega dealer kindly agreed to lend a Rega phonostage next weekend to take home and replace my Linn Linto to help isolate the guilty component.
Assuming this doesn't help, the next step would be to try a new MC cartridge. 
Would a Rega Ania MC cartridge that costs more than 600 pounds be a golden ring in a pig's nose ?
Again, assuming it solves the problem, wouldn't it be more economical to just sell the TT and buy another one that fits my phonstage/system ?
I was not aware the Rhondo Red was a moving coil cartridge. At this price point you are much better off with a Moving Magnet cartridge. As an example you find the Gyger S stylus, perhaps the quietest tracking stylus made in the $17,000 Clearaudio Goldfinger MC. You will find the exact same stylus in the $600 Goldring 1042 MM and a similar stylus in the Audio Technica VM760SLC for $600. 
That cartridge is pure CRAPOLA.  Get a Grado Gold (MM) and listen to how sweet a P3 can sound.

Problem solved ! Well... most of it ...

I decided to start the Rondo Red setup from scratch. All I knew is that the dealer who sold it to me used a Baerwald protractor for Rega to set the Cartridge alignment. I read that a Stevenson protractor for Rega can be better. I used the Stevenson and bingo ! Now there is a nice Bass, drums have a decent attack and sound stage is much much better. I ended up spending 8 hours yesterday listening to my good old vinyls.

The sound though, is still on the bright side. When Barbra Streisand sings "Memories", at timing 01:38, sound is too bright:
https://www.youtube.com/watch?v=MWoQW-b6Ph8
In a climax part of a symphony wind instruments sound a bit too bright.
So at this point I finally end up enjoying my P3 TT but sound is a bit inferior to my Digital department (Linn Karik transport + Carry Exciter D/A) .

Bare in mind that my Linn Linto phonostage is MC only so I'm afraid MM's are not an option for me.
To resolve the brightness issue, I have to buy a better MC cartridge like the Rega Annia for 800$ or similar.
Anybody here tried the Annia MC ? Any recommendations for a decent MC ?