The transistor amps will not give you what you want , in my opinion. I have been a confirmed user of transistors since I built a Heathkit in 1963 and was a Quad dealer for 15 years. Transistors are undoubtedly faster on cone speakers , because of higher dampening factor among other considerations. But these factors do not apply to the Quad, which is already faster than any cone. When I was a dealer I drove my 63s with Krell, Musical Fidelity and Stax class A solid state amps but could not detect a difference in speed or bass between them and good tubes. A friend drives his 57s, which I sold him in 1975, with a rebuilt Heath tube amp , it sounds as good as anything I have ever heard drive them. Foster Blair rebuilds them, they are available through Mapleshade. This is one case where having a transformer in the line helps the sound. After all, they were designed with a lower powered tube amp in mind. If I wasn't happy with the sound of the 57s driven by a good tube I would look at another speaker, they are what they are and the amp will not change them that much.
