EL-34, KT-88, 6P3P: What's the Bloody Difference?

I am about to purchase my first (budget) tube integrated amplifier.

Now, I will not be able to audition any of these.

Here they are:

Prima Luna Prologue One: 35 watts; EL-34 output tubes
Prima Luna Prologue Two: 40 watts; KT-88 output tubes
Jolida 202A: 40 watts; EL-34 output tubes
Jolida 707; 40 watts; 6P3P
ASL AQ1003DT; 30 watts; EL-34 output tubes

Notice three different types of output tubes are used:


What's the sonic difference between these types of tubes? Why choose one type of output tube over another?

Many thanks for any guidance you can give me on this!

Do some research on this in the Audio Asylum tube forum, and/or post this request there. You have a better chance of getting some good responses. IMHO the design of the amp is more important to the sound than the tube's designation. However KT88's, 6550's, and KT 90's, for example are large power tubes and unually produce up to twice as much power, ergo when a manufacturer wants to build a high power amp they choose these tubes. When high power is not an issue they use EL34's etc. The Primaluna is an exception and I think that the use of the KT88 may produce a tighter and more powerful sound even though the power delivery isn't that much different on paper. Why not call Kevin Deal and ask.