I have a Rhea and love it. With a 0.3mv cartridge you are getting to the point where some Rhea's can become noisy, depending on tube selection and maybe age/version. Perhaps the newer ones are quieter, but my 5 year-old Rhea exhibits a bit of tube rush with very LOMC cartridges. I'm quite happy with it, but if you want absolute black backgrounds, you might prefer the Pass, which is definitely quieter.
With a Shelter 501 @ 0.5mv mine is very quiet, but with my low output Dynavector 20xl, I can definitely hear the preamp on very quiet passages or between tracks.
That said, I think the Rhea provides a richer harmonic structure, and it is certainly my preference. Depends on what you value most.
Hope this helps!
