Cary 805, deHavilland or Atma-Sphere? Anyone cares

FWIW, the deHavilland SETs are some of the very best SETs made in the US. Also, as far as bass is concerned, Atma-Sphere amplifiers are full power to either 1Hz or 2Hz, depending on the model.

In either case of SET or smaller OTL, the speaker choice is important- the amplifier investment dollar will be better served by a 16 ohm speaker as opposed to four ohms (in fact transistor amplifiers sound better on 16 ohms too; there is not much argument for four ohm speakers if better sound is your goal). Some help in understanding what is up can be found at
http://www.atma-sphere.com/papers/paradigm_paper2.html

The Magnaplaner 3.6 is not particularly hard to drive, but it is not efficient enough to really work with any amplifier that is limited to say 30 watts or less. The Speltz autoformer is a good combination with larger tube amplifiers and the Maggies. We have a number of customers that use the 3.6 with our M-60s or MA-1s and the Speltz ZEROs. This combination turns up an awful lot- I used to think that it was a local thing since all of these products are made in Minnesota, but its not. They just work really well together!

Sorry you are having disappointment, but FWIW, 9 watts is not enough power on that speaker! Tannoy recommends a minimum of 50 watts and given the efficiency that sounds right.

The problem you may also be up against is that 50 watts is not going to show off the speaker if you have an SET. This is because at power levels like that bandwidth is going to be sacrificed in an SET; it is the limitation of the technology that you can have power or bandwidth but not both.

This is a problem in particular if you want the speaker to play bass (and have plenty of headroom)! If I were you I would look for a push-pull amp, something triode if you can. Our customers have had good luck with the M-60 on that speaker. Getting a 60 watt tube amp to play deep bass is not challenging. You also get more extended highs.

Good Luck in any event.

Dracule1, 6 ohms is not a problem for the M-60. As far as the ZEROs go, they should be considered a problem solver.

People often try to use the amps with speakers that they were never designed for. The ZERO helps with that. But if you have an 8 ohm speaker you just don't need them.

I should point something out here. With regards to impedance and amplifiers in general, there is no argument for 4 ohms or less (all other things being equal) if your goal is the best sound reproduction possible. Even transistor amps don't sound as good driving 4 ohms as they do driving 8 ohms as their distortion is higher (which the ear hears as strain and brightness).

Now the Tannoys are a proven easy load for tubes, and we've yet to run into a set that the M-60s won't drive.

BTW, and FWIW, most tube amp manufacturers warrant their tubes for 3 months. Our warranty is 1 year.