Tube preamp topologies and music

In my tube amp collection I have several single-end amps: a 45, a 2A3, a 6BG6 and a 6L6GC. The last is the Golden Tube SE40, which uses three 6L6GC beam tetrodes per channel to yield 20 watts. Much more usable than the 45 (1.75 watts), 2A3 (3.5 watts) and the 6BG6 tetrode (7 watts). 

Perfect thanks. That makes sense.
So Probably a push/pull design would fare better? What role do the tubes play in this say a push/pull kit-88 (Air Tight ATM-2) vs a 211 push/pull (LampizatOr)?

The radio-transmitter tubes - 211, 805, 845 - require high plate voltages on the order of 1K + volts DC. Building output transformers able to handle a kilo volt without insulation breakdown is difficult. Plus having such a high voltage circuit in a chassis makes it a potential execution device!

Push-pull can have superior signal-to-noise (SNR) ratio and less harmonic distortion due to the self-canceling effect of a balanced circuit. Also there is no DC current flowing in the output transformer of a push-pull circuit. 

AudioXpress magazine had a good article on building a single-end 211 amp some years ago. The authors cautioned that such a project was not for the inexperienced! I suggest you track down this article! I no longer have my copy. Another valuable source of information on tube amp design are the issues of Sound Practices - recommended! Lastly, find issues of Glass Audio - more information on design and construction of tube amps.