Best 300B tube for Cayin 300B amp?

oceanica...i just replaced my previous sophia 'princess' with the new sophia 'royal princess' and it is much-much better. read the new review on positive feedback magazines website by jeff day...it really is great.i have about 20 hrs on them and they keep improving but right out of the box were significantly better...soundstage..bass ..mids ..everything...

Calloway, what amplifier(s) are you using with them? Since the OP stated their amplifier of choice for usage in. I recently bought a barely used matched quad set of "royal princess" for use in my Wavelength Cardinal XS amplifier pair.
Oceanica, My amplifiers are too recent to me to have tried different tube pairings, tho, I earlier purchased a pair of Shuguang Black Treasures. I have no complaints with either, but have been too busy enjoying the music to exchange for an attempt at a comparison. I suppose this was not much help:) Interested in your future findings.

Clarification: Wavelength Cardinal uses one single 300B per mono amplifier. Pair in use and back-up pair. Nice:)

isochronism....i have chalice audio 'grail' SET monoblocks...chaliceaudio.com...the 300B tubes..1 each amp..are the driver tubes in this configuration...( see pic in my 'system' area)..the 'royal princess' tubes are not cheap...~ $ 1200 / matched pair...but they are much better then the sophia 'princess' tubes they replaced and worth the price..hope this helps..dave

Occanica,
You don`t mention a price range,300bs can cost anywhere from 150-2000 USD.A competitor to the Royal Princess in it`s price range is the Takatsuki TA 300b(Japanese).
EML XLS and mesh 300b are very well regarded.

I`ve been using the Shuguang Black Treasure for two years and it sounds fabulous and has been absolutely trouble free. For 600 USD they`re worth every penny.
That new Takatsuki is very intriguing.