As a big Usher fan I have to tell you way to go! The BE 10/20 are amazing!
I had the 7.5 in my system and I switched over to the SLP 05 and I thought it was dramatically better than the 7.5 wider deeper soundstage, more liquid, more involving.
For the price difference you could buy the Cary and the new AMR CD 77 probably the greatest value in high end cd players ever to exist!
The SLP 05 is in an entirely different league compared to Cary's past preamps which were no where as transparent or balanced in performance, and it is a good deal at the price.
Also the Acoustic Zen cables are excellent you can get better performance for less money with the new Synergistic Tesla series.
I haven't heard the ARC in my own system so I can't comment but it is supposed to be a great preamp although the traditional ARC sound tends to be more analytical.