I just got my new Cosmos tonearm board back from Sota predrilled for my new Helius Omega tonearm. Mounted it on my Cosmos IV with a Lyra Delos cartridge. This arm replaces an SME 309 that I thought was a very good match. To say the Omega is an improvement is an understatement. I really didnt expect much difference. But from the very first album after setting the arm up, the Quality Brubeck reissue of Time Out, it was obvious to me, my wife and her visiting daughter that this was the best reproduction we have each ever heard in the home. Simply on a different level than the SME309, which I thought was very good before, and probably still is. I would have never expected such an improvement from just changing a tonearm and while I can hear an improvement over a Rega RB300 to an SME309, the improvement is subtle. This was not.
Its too bad Helius is not better known here in the States. Its a great arm.

Now I have to put together my Russco/Schroeder Clone arm to see how it compares
After a weekend of listening, my original impression stands. A very nice tonearm.