2A3 vs. 300B single end triode....

2A3 is a bit trickier to use but if your speakers are high efficient then the 2A3 will sound a lot better than the 300b.
When using triode tube, smaller(I mean power output) is better(better sounding).
Personally I'm using 245 triode for the mid/high of my bi-amp system. The 245 just blown the 2A3 and 300B(original WE 300B) away.

If you really go for the SE Triode thing, you should get yourself a pair of highest efficient speakers that you can get or build and then you can play with any triode tubes you like.

Cheers.................

Twl above:"Much depends on the amp design that the tubes are in"

I agree with that.

Below is a comment by Lynn Olson that has cauesd me to experiment with the driver stage a bit. I think it is harder to put a finger on what exactly is causing a particular sound than is sometimes thought.

quote "My limited experience so far is that drivers actually contribute a stronger sonic signature than the output tubes, which are pretty transparent if driven by a low enough source impedance and low distortion.
Arthur Loesch tracked me down at the CES a few years ago, and as we chatted and toured the rooms at the Alexis Park, he mentioned that most DHT's sound alike - if driven by a low enough source impedance and a powerful driver with *lots* of current. It's when they are driven by feeble 5-8mA driver tubes that the characteristic 45, 2A3, 300B, or 845 signature appears. In other words, you'll get loads of that 300B sound if all you're using is an RC-coupled 6SN7."
end quote Lynn Olson

The guy is no fool. Something to consider anyway.

I remain,

Clueless,
How about a choke-coupling from 6SN7 to 45?
With battery power, and ZOTL output from the 45s?
And DHT with 250kHz AC on the filaments?

Craig, I'm just teasing. I love this amp!
You guys are the only ones that I can share it with, because nobody else I know can even comprehend what I'm talking about with this amp. I hope you don't mind that I mention it from time to time, because I just need to share the joy that I am getting from it.

I'm a dealer, so beware! But I had to put my 2 cents worth in. My Sophia Princess 300 B uses a 6SL7,El-34,and 300B.Best I've heard yet, But I've not heard them all. So take it for what it's worth.