I have a Carver M1.5 and I love it. I use big, power hungry Transmission Line speakers (IMF RSPM Mk IV, 80dB efficiency) and it works perfect. Very quick amp, and tons of power for those low frequencies.
Also with regards to the TF2000 transmission line - I do not believe it is a true transmission line. The length may be correct for the Fs of the driver, but a true transmission line is at least as deep as the surface area of the cone of the driver. The DCM TF series is too flat to allow for that - that's why you see most transmission line speakers are rather large and bulky. However from what I do understand of the DCM TF series it is a well designed port, regardless of what it actually is or not what matters is that it sounds good. I just wanted to point this out though because the DCM TF series wouldn't have the same sort of power requirements as a true t-line. I believe this is why the efficiency on the DCM TF speakers are much higher than a traditional transmission line of the same era.