2a3 ?

SETs have a limitation of the greater the power, the less bandwidth is obtained from the output transformer. 7 Watts (300b) is a practical upper limit to what can be considered 'hifi' bandwidth. The 2A3, being good for about 4 Watts, allows the designer to have a wider bandwidth and therefore less phase shift (which can be heard in how the sound stage is presented). The reason the type 45 has ascended the throne in the last 20 years is for this very same reason.

A pair of 2A3s in push pull can produce about 16 Watts, making for a more practical amount of power. If the circuit design is good, it will not cede anything to an SET; quite the reverse.

If you want a lusher sound from 2A3 invest in a pair of dual flat plate 2A3's.

Mine are branded Ken Rad with blackened glass from just above the flashing to the top (wide) edge of the tube.

NOS have a tendency to measure higher than most other 2A3's - like just above 80 on a TV-7D/U (my engraved base Visseaux 2A3's also measure about that).

DeKay

Good call Atmasphere. I owned the Melody i2a3

running 4x parallel 2a3's for 16-18 watts. A superbly

built amp (why did I sell it?). I have the speakers to

take advantage of five watts or less so no issues there.

I believe I understand single ended theory but doesn't True 

Class A single ended come from DHT tubes? Are amps

using el34, el84 and various KT's claiming single ended

actually pseudo single ended? I consider Wrights

2a3's true single ended whereas a Dennis Had

KT88 is pseudo? I've owned both but can obviously use

some schooling.

Loving my Whammerdyne DGA1 amp pushing out just over 4 watts per side, with ultra wide bandwidth transformers (14 Hz - 50k Hz +/- 3 dB). If you are near Atlanta, GA, you are welcome to stop by for a listen.

I have heard some SET amps running the big transmitter tubes, including a 1610 tube, and I have not heard any that surpassed the lower powered SETs when playing speakers of high enough efficiency such that no amp was being forced to play out of their comfort zone.  Yes, some 211, 845, 833 amps sound pretty good, but I still like the 45, 2a3, 300b amps a bit more.  

I never ran my parallel SET 2a3 amp into hard clipping, but, I did suspect it was slightly compressing peak volume when playing certain kinds of music.  This appeared when playing large acapella choral works at somewhat high volume--no obvious distortion but the music sort of stopped getting louder at peaks (99 db/w speakers).

I don't agree that, even with very efficient speakers, SET amps always win over pushpull.  There are certain pushpull amps that deliver the same sort of natural, harmonically dense and complete sound of good SETs, while sounding a bit more punchy and dynamic.  There are also contenders from a completely different camp--the output transformerless (OTL) amplifier.  The incredible dynamics and liveliness of good OTL amps can be extremely captivating, and they deliver this kind of sound without necessarily being bright or harsh.  I don't think any particular topology beats another; it is a matter of taste/priorities, system matching, and specific execution of the topology.