Questions Regarding Installing a Wheaton Triplanar On A SOTA Cosmos

And of course if you really must have very low effective mass, there is always the ADC LFA2, 6g total.

https://www.vinylengine.com/library/adc/lmf-2.shtml

Three of my favorite cartridges have very high compliance, the Ortofon MC2000, which vexes the OP, the Acutex 320 series (LPM and M versions, with a compliance of 42), and the B&O MMC1. The latter two are easier to satisfy than the MC2000, since they are intrinsically light weight; whereas the MC2000 weighs 11g all by itself  In practice, I have successfully used tonearms in the low range of "medium" effective mass with all of these.  I'd try a suspect pairing before going on to turn a tonearm with interchangeable headshells into a fixed headshell type.  In a pinch, that CF headshell you have unearthed or an old super light weight aluminum headshell, e.g., SME, would be worth a try.

I have tri-planar on my clear audio innovations woody and love the synergy.  I have the 9.8 inch arm and have another that I want to mount a mono cart on down the road.  You may want to investigate this combination as I see these come up for sale a few times a year, pm me if you would like to discuss.

With Drone Technology developing at the rate it is, Maybe ??? the Tonearm as it is known today, has a new tech to be utilised, that will transform the way the Cart' is to be enabled to track the LP Groove.

Watch this Space.

I do like the Triplanar arm. For an arm that has so much adjustability I don’t see how to adjust the cue lever bar. This one wants to drift a bit on set down and pick up. From searches on the net this seems to be an issue others have had. With the only fixes seem kind of janky. Wish there was a way to level that rod.

Tri at Triplaner is quite responsive 

I suggest filling in the armboard hole with bluetac. Does your Dynavector arm have cueing ? IF so….. i know somebody who NEEDS that….. ha