Atma-Sphere M60 or David Berning ZH270?


Hi, I need some helps to decide which one of these two amplifiers to go with my 14ohm Coincident Super Eclipse (SE).

The Atma-Sphere seems a perfect match for the SE at least in impedance matching and at 14ohm, may get more power than 60 watts. The ZH270 may get less than 70 watts @14ohm. However, I have the following concerns for the M60:

1. 8 6AS7 output tubes per side generates a lot of heat and it does not have cage protection. This is quite a problem if you have young children at home like me. The ZH270 has tubes internal (like a Tube preamplifier) and thus safer for young children.

2. 16 6AS7, though last long time, can be more expensive than ZH270's 4 6JN6 if I try to replace them.

Pro for ZH270 can run without a preamp and is auto-biasing.

On the other hand, ZH270 is more expensive ($4995) than M60 MKII.2 ($4250) (current still have a few left).

As far as the most important factor: sound? I have no idea at all. I have not heard either one anywhere. I have owned ASL Hurricane for over a year and like the sound very much but disappointed for the constant re-biasing and QC problem.

Does any one have Reliability problem with either one?

My listening room is 13Wx8Hx26L and I listen almost only classical music from solo violin, piano, to chamber music to 20 century's big symphony orchestra works (Mahler, Strauss, Stravinsky, etc.).

Thanks for the helps.
laoyuap
I heard the Atmosphere and the Berning in the same system but not at the same time(A/B). In purely sonic terms, the Atmosphere edged out the Berning except in the bass. I thought the Berning had more PRAT. Otherwise, in all other matters--heat production,tube replacement,tube biasing,electricity bills,and especially compatibility with a wider range of speakers, the Berning wins hands down. Since I live in Florida, heat production was a crucial factor(I mean ALOT of heat). I ended up with the Berning and enjoyed it very much. If heat and speaker compatibility weren't major issues, I would have bought the Atmosphere amp. You won't go wrong with either amp. Enjoy listening.
Laoyuap, here are the mods to the Bernings that I have: 1. All tubes replaced with NOS, some cryo'd, some not, not really a mod I guess, I think that new Bernings come with the Cryo'd 6jn6 tubes stock now, not sure

2. The ERS mods

3. Some of the caps have been replaced, again maybe that is stock now, not sure

4. The silver wire mod that Allan mentioned to you.

Also, since I have two 270's I run as monoblocks, I had some internal rewiring done to bridge them, but that's obviously not an issue with one amp.

I feel like I'm missing something, but I guess not.
Just my 2-cent as an Atma-Sphere owner. Unfortunately I have no experience with the Berning amp.
I put a pair of M60 MK2.2 into my system this past July and in a matter of days decided to sell my Krell monoblocks that I have happily lived with for more than 10 years.
To my ears the AM is simply "truer" and "righter" than anything else I have listened to as far as timber accuracy and tonal balance go. It has none of the problems I've heard from other tube amps possibly in part due to AM's elimination of output transformer. Both extreme ends of audio spectrum are well extended and defined, sound stage and imaging is also as good as any I've heard. This all from pairing it with a pair of less than ideal speaker with a nominal 4-ohm impedance.
The reliability has not been an issue. It never missed a bit from day one.
There is also something to be said about the benefit of completly point-to-point wiring without the use of PCB. This also opens up the opportunity for future tweaking and upgrading if you are into the sort of things.
I like it so much that I am actually in a process of getting a pair of MA-1 Silver to better match my speakers.
Hope this helps! Best of luck and happy listening!
Laoyuap, yes, my Coincidents are modded. The mods are quite extensive.

The original Vifa tweeters were replaced by ScanSpeak Revelators that I got from Israel. The Seas midwoofers were completely rebuilt by the BEST speaker guy in the world - this mod is more significant than I can explain to you. Let's just say that naturalness, speed, and slam all jumped up several steps. The wiring was replaced. The cabinets were damped, but not overdamped, and stuffed. What was a very nice speaker came to realize its full potential.

And, OTL amps have always been rare. If Coincident wanted to keep going in that direction, nothing would have stopped them.
Hi, Gentlemen. Thanks a lot for your suggestions.

I have decided to try the Berning and enrolled me in Allan's waiting list. It seems both are good amplifiers. For my limitation, Berning is the only choice.