Everyone should own a 300B amplifier once in a life! I am one of them. This is quite a big and costy project and I use all the good stuff that I can afford at the time – Lundahl transformers, choke, Jensen Cap, Elna caps, Multi-cap, Rifa cap, telfon wires and Full Music 300B tube etc… Total spend on that is about US$1200!
Full music tube is lack of bass. Recently I buy a Quiguang 4300B and the bass is much better and firm. The 4300B cost about US$120 per pair. I think 300B to drive mid and high frequency is one of the best sound amplifier!
Update: Oct 1st, 2010
The 300B was upgraded with Russian PIOs, see first picture. FFT measurement is attached below: