According to the late Harvey Rosenberg, President of New York Audio Laboratories, the OTLs were designed with Quad 63's in mind. I used to be a NYAL dealer and found that the OTLs mate well with most good (high impedance) loudspeakers. If your listening tastes run along the lines of light jazz or classical and your listening room is on the cozy (read, small-ish) side, then the Stax F-81s with OTLs are a match made in heaven. One of the two most memorable experiences I've had in audio was listening to Oscar Peterson through this combination of magical components (tho' the 63s do quite a competent job as well).
Before purchasing a used pair of OTLs, however, be sure to verify that the amps properly bias and balance. The 6 output valves should be replaced with matched sets (if/when needed) and these amplifiers can act very strange when kitted out with unmatched power valves. Also, if you're comfortable with a soldering gun, I'd highly recommend replacing the 10 or so square, red capacitors with exact value matches of the best current "magic" caps you can find. This single modification is relatively easy to perform and will yield a noticable improvement in the amp's overall transparency and speed.
Good luck,
David
p.s. If you're interested, you can read some of Harvey Rosenberg's last articles on audio at: http://TriumphPC.com/psst!/jun01
Before purchasing a used pair of OTLs, however, be sure to verify that the amps properly bias and balance. The 6 output valves should be replaced with matched sets (if/when needed) and these amplifiers can act very strange when kitted out with unmatched power valves. Also, if you're comfortable with a soldering gun, I'd highly recommend replacing the 10 or so square, red capacitors with exact value matches of the best current "magic" caps you can find. This single modification is relatively easy to perform and will yield a noticable improvement in the amp's overall transparency and speed.
Good luck,
David
p.s. If you're interested, you can read some of Harvey Rosenberg's last articles on audio at: http://TriumphPC.com/psst!/jun01