Zero Autoformer good/bad for Atma/Quad combo

I have Atma-Sphere MA-1 amps connected to Quad 988 electrostatics. I know the older Quads and the M-60 amp benefit from the usage of Zero Autoformers. But there is not much info (from the Agon or AA forums) whether the larger Atma-Sphere amp (MA-1) and/or Quad 988 would benefit from the Zero or not.

I believe the Quad 988 impedance curve is only below 6 ohms between 4K and ~16K Hz with its greatest dip to about 4 ohms at about 10K Hz. And between 70 and 150 Hz the curve spikes above 16 ohms. The Atma-Sphere MA-1 cranks out 165 watts into 8 ohms (much more power than Quads can be cranked too) -- so...

Would Zero Autoformers offer any sonic benefits to this set up?
It might, but you will not really know until you try them. I have found varying degrees of success with these on different tube amps and speakers. I have a nice pair I was thinking of selling. Interested??
I would give Ralph a call to get his opinion on this but I think he will see the thread and post his response.
I think you would not need them as the drop is at the higher frequencies that don't require a large amount of power.
I did use the "Zero's" with the M-60 amps driving a pair Acoustat 2+2s electrostats. I did call Ralph and he did endorse them. In fact I posed the question "are the M-60's capable of driving the Acoustat speaker" and he suggested the Zero's. He must have spent at least 15 minutes explaining to me the reasons why, much of the time over my head. As stated in one of the above posts, "truly one of the good guys within the High End Audio industry.......
If I had to use Autotransformers with the Atmasphere, I think I would rather use a regular tube amp that has transformers built in. Defeating the purpose.
different kind of transformer... Does not defeat the purpose of a OTL. But, having said that, it is adding something else to the chain.
No, I would not expect any benefit from using Zeros with MA-1s driving 988s. M-60s might be a different story, but I would try them with and without.

M-60s drive Quad ESLs (57s) quite well without need for Zeros.
Jwm, just for the record, all ESLs have an input matching transformer. So if you used a set of ZEROs with a transformer coupled amp you would be passing the signal through three transformers if you were using ZEROs.

Even though we are an OTL manufacturer, (IOW if I say so myself) the use of the ZEROs **does not** defeat the purpose of the amps! A transformer like the ZERO would not even be possible if you did not also start with an amplifier that already has a low output impedance, since the ZERO loads the amps at 16 ohms.

Because of the very low turns ratio, the bandwidth of the autoformer is from 2Hz to about 2MHz- wider than almost any amplifier made. Even transistor amplifier manufacturers report that their amps sound better driving 4 ohms through the ZEROs rather than direct. The lesson here seems to be that while a transistor amplifier might double its power while driving 4 ohms, that is not the same as saying it sounds its best while doing so.

The same is true of tube amplifiers- the ZEROs can be regarded as a problem solver or assistance to any amplifier that has to drive a low impedance (so long as that amplifier does not make power too excessive for the ZEROs). So, it would be one thing if only OTLs benefit from ZEROs, but when **all** amplifiers do, its hard to say that they defeat a purpose :)

In the case of the MA-1s, they are a big enough OTL that it is hard to say if the ZEROs will help. Certainly with M-60s they do- the later Quads tend to have a generally lower impedance curve than the earlier 57s and 63s (which don't seem to need the ZEROs).

Have a Happy New Year!
Thanks for the input Ralph and everyone else!

So, I auditioned a set of Zero's (at home) and honestly I did not hear a beneficial difference in my system. Now, I'm NOT saying the Zero's aren't beneficial, there are definitely impressive experiences out there. I just did not find them helpful in MY specific system.

I tried the 2X, 3X, and 4X taps, tried running them over night, tried one speaker with / one without during mono playback... And what I heard was;

the 2X tap is VERY close to without. It does smooth out horns and dynamics -- not to my liking though. I feel like something "real" has been taken away and replaced with something "hifi". The dynamics began to sound slightly compressed, loosing the "punch" of say - drums. Horns were more sweat, some of that brassiness was lost.

The 3X tap moves voices forward on stage a bit. But, again, increased the dynamic smoothing described above.

The 4X tap brings voices forward more. But more-so flattens out liveliness.

Thus, for my liking, I couldn't see keeping them. Appears my system must be matching up well, I do have the MA-2 Power Caps installed in my MA-1's -- I don't know if that makes a difference, but nonetheless, I reckon I'm not experiencing any impedance problems...

On a side note, I say that Paul, at Zero Impedance, was the best -- he got the Zero's out to me fast, offered fast assistance / advice, did not question their return, and was fast reimbursing me. Absolutely great experience, even though the Zero didn't work for me. Thanks Paul (if you ever read this). --So, for anyone else considering the Zero's, trying them out is pleasurable to do.