Hi:
Hopefully I can shed some light on the T6 and T7 for you:
The Transcendence Six is a hybrid tube amp that uses very fast solid state current buffer. The buffer is driven by the tube and isolates the tube from the loads. Using the high speed buffer adds a lot more dynamics than what is offered in the T5 (now discontinued); therefore, you get a much more transparent sound.
The Transcendence Seven is a significant redesign of our original Fet-Valve design. The tube drives a MOSFET, and again all is isolated from the loads. In the T7 the dynamics are again increased, the transparency is increased, the noise is decreased, etc. The T7 is the purest preamp we have ever built. While it's true that both preamps use the same tubes, the solid state design around the tube is what differentiates the two products.
As for chassis options, the T7 is available in the SL chassis (no tone controls) or the EC chassis that has more inputs and switchable tone controls. The T7 has higher gain and therefore we can offer it with tone controls. With the tone circuits you need to be able to boost parts of the sound (bass and treble controls) so the preamp has to have the extra capability which we were able to get using the Fet circuitry. The T6 is only available in the SL chassis. We looked at doing tone controls in the T6 but felt it compromised the sound too much for our liking so we stuck with the SL chassis with no tone controls for that model.
You may have noticed that I said the T5 has been discontinued. The T5 is a very fine product -- even outshining our original FetValve preamp; however, when we looked at the cost to manufacturer it and the T6, which has a much better sound, we decided to only offer it as an upgrade to the older Super Pas 3i and Super Pas 4i. We lowered the price of the T6 and are now offering the T6 in a kit for those that like to melt solder. We have a new catalog at the printer and the Web site should be updated about the time we get the catalog back. There are some more interesting changes that we'll tell you about very soon...
Thanks for your interest in AVA products!!
Larry Jenkins