Before you respond I have had a 300b and that is definitively not my cup-o-tea.
You have a 300B? What do you mean...you have an amp that uses 300B tubes? SET...parallel...or?? You need to be a whole lot more specific there...all amps that use 300B tubes are not alike. There are so many things that go into the design and build of any amp and the output tube is only one element. Nor are all 300B tubes alike...an amp may sound awful with Shuguang tubes and wonderful with WE's. It would probably help others help you if you specified which amp you have, which speakers you use them with, what kind of range of music you listen to, and what it is about what you have now that is "not your cup of tea," and why you are drawn to wanting to try SET (or SEP or ...).
What you've stated is kind of like saying "I really want to get a sports car. Before you say anything let me tell you that I currently have a V-8 and it's really not my cup of tea."
I'd echo Larryken's advice - SET asylum will have plenty of experience to answer a broad range of SET-specific questions.