I'm not sure what SOTA is but it sounds like you have a really nice turntable.
I was recently looking around and some trusted people recommended Shelter cartridges to me. I read reviews that remarked at how neutral they were. However, they were a bit out my range... but are in yours.
I'm quite pleased with the Dynavector 10x5 I bought, it works well on my Pro-Ject arm... Is there a style, weight, size, etc. that the Graham arm works well with?
Have you done any searching on AA for cartridges that might work well with the Graham arm? I have found the cart, arm, preamp combo has been a very important 'synergistic' match. (in that order)
Good luck,
Carl