OK, a small review/comparison between my stock EL34 valves and Johnjo's borrowed set of JJ KT88's

Where to start...?

Treble
Really improved level of detail in the high frequencies with masses of control and precision. No glaring brightness as there was with the EL34's which I have to say bordered on hardness and glare. KT88's really are a massive improvement

Midrange
A really laid back midrange via the KT88's in which it is so easy to hear the stop and start of synth pads on George Michael's Older album. It is also much easier to hear the multi layering of synths as well. The stereo effect with the KT88's is truly massive and much better defined but vocals now sound more distant which adds a degree more depth. On Bowie's Blackstar the drums/drum machine is extemely tactile with an easy to hear skin decay on the lower frequency drums. The midrange has much more 'pop' to it in a propulsive way

Bass
The bass extends about another octave and this extra bass is really obvious but in a well controlled way. Very tight, extended bass just the way it should be. Much more propulsive than with the EL34's with amazing clarity and power

The KT88's have amazed the most with their phenomenal detail and resolution

Incredible really

Massive thanks to Johnjo