Hi Rob,
SE rocks indeed (and does every other form of music very well too!) As you might imagine I've had all sorts of exotic 300b SE amps through my workshop from Shindo D'Yquems, to other Japanese, UK, and US exotica. Yet the SE amps I've chosen for my home use are not 300b driven but use 845 and 805 output tubes. Why? Because these amps have decent outputs of circa 50 watts and bash out the frequency extremes with much more realism than a 300b can manage without losing anything in the mid range. In the lounge I've got Mastersound 845 PSE monoblocks, while in my studio I've got modded Ming Da 3008 Cavatinas with 805 tubes. If I were you, as indeed I did, I'd score myself a pair of Ming Da Cavatinas new around £4k or secondhand around £2k and even without a few judicious mods you've got a great performing amp. To my ears, the 805 tube is the great unspoken find, giving around 50 watts per single output tube and more inner music insight than an 845 or 300b. There's enough grunt and drive for any sensible speakers and believe me either of these amps provides massive scale and dynamics that no 300b or 2A3 could ever match. The 805 Cavatina uses 300bs as driver tubes so in fact you do get that 300b magic along with all the benefits of the 805.

You're not going to get valve rectification for these output tubes but as I've proven the difference between properly designed solid state rectification and tube rectification cannot be identified in A/B testing when voltage is matched. Changing to solid state rectification is quite a common mod now the real classy rectifiers such as GZ34 are getting so expensive. You're very welcome to a listen of down this way
David