I just compared a Rega Aria with the Graham Slee Accession MM phono stage, and the Slee was a clear winner in my system. Wonderful detail without harshness, dynamic, and just sounded like music. I have it paired with a Rega Elex-R, and an Acoustic Signature table with Rega RB 330 arm. It's a great match. If you like the Slee that you have, I would heartily recommend moving up to the Accession. If you can purchase from Music Direct, you will have a generous return period in which to audition it in your system.
Cheers, Scott
Cheers, Scott