Tone Arm Mass

Hello world. So here's my issue. (Well, one of them.) I have a Well Tempered Classic table with the carbon fiber arm, and a shelter 901 cartridge. I spent much time setting the table up, and was not satisfied. Lowing VTA, raising VTA… aligning and realigning … The lower mids and bass just were just weak.

Then I read about a thing called "compliance."

The Shelter is low compliance, which means that it should have a more massive arm – at least more massive than the WT. I bought a 3gm headshell weight, and low and behold, more bass, more life – I finally felt I was hearing what the 901 was capable of.

Thing is, I think if the arm had still more mass, it would improve the sound. Specifically, make the lower octaves more pronounced. More bass. What say you all?

How would I go about adding mass to my existing tone arm (buying a new one, or new table is unfortunately out of the question at this point.)

The rest of my system:

CAT SL Mark III preamp (100 ohm load on the 901.)
Quicksilver v4s
Vandy 2CE Sig
PS 300
Richard Gray 1200

Thanks for your time!