David Berning ZH-270, stable into 2 ohms (maybe a little less), does not use up alot of power and has way more bass than most of the other OTL's you have mentioned, also utilizes quite possibly the most advanced power supply within the audio realm. It also INCREASES output power as impedence curve dips, not the opposite like the other OTL amplifiers. You may also adjust feedback on the fly, auto biasing, has A/B input switches for use direct with a source if thats what you wish, boasts a 20 year life span on tubes and uses way, way less idle power and less power at full ouput than the other power mongers out there. You may also utilize the channel strapping option with (2) ZH-270's which will provide you with 105W @ 8 ohms. My single 270 is happy as ever running full-range Soundlab Pristine ll's with no problems. What other amplifier that weighs 9 pounds puts out enough power to drive full-range SL's?? Notta, none.
Best of luck,
Chris
Best of luck,
Chris