Recommended Speaker List for Atma-Sphere OTL Amplifiers.

My concern with Klipsch speakers would be possible dips in the impedance curves of each speaker. Efficiency is only part of the issue.

When we compared the M-60s to several SETs the results were significant. The M-60s were like water while the SETs like chocolate milk. The other thing that we found is that even the 20 watt parallel single ended amp ran out of steam very quickly and started to distort in a very obvious, albeit pleasant way. 

I personally was thinking mainly on impedance more than in sensitivity terms, you are correct impedance is big part of it, most of klipsch is usually 8 ohm nominal and above 93 sensitivity, I have P37f as secondary speakers and very easy to drive with the Atmas, mains are AudioKinesis which are 95 dB and 10 ohms.Anyway, could you recommend me an amp like bourbon? Not much into chocolate milk.
Joking aside, the preamp used could have a lot to do with your SET comparison but I have to ask which type 300b?

Actually we used an Audio Note 300B, an Audio Note Kit 300B parallel single ended, a Mastersound 32B (crushed the other SETs). VAC Phi 200 and Atmasphere M-60s. Preamps used were Essence Jasper, CAT, Audio Note, Thor Audio and an older VTL. The preamps universally sang the praises of the M-60s. To understand the inherent limitations of SETs you need to compare them with an OTL. You will instantly hear the limitations of the transformers, the inherent problems with the lower power and the quick clipping which sounds like the amp is producing power but it is really a bunch of gunk. The push-pull VAC did very well , but lacked the texture of the Mastersound and was completely outclassed in every way by the Atmasphere. Most of the listening was done on a pair of DeVore 0/96s which is a very easy OTL friendly load. 

Thank you, I asked because I can't comment on the 300B SET as I haven't had a chance to compare one on my system, I have a PSET in which I tried many different tubes combinations (not 300B) and when it starts clipping and distorting is not very pleasant, still better than a SS but obviously distorted. The Atmas on the other hand (and this is not apples to apples as I have MA-1s) are wonderful driving 10 ohm speakers.
If you are listening to low volume the PSET is pretty good.

thanks guys for answering in this older thread. 

luisma31 thank you for the tube quantity information. 

I believe the M60 Mk2’s i’m looking at have the mk3 upgrade already if not I’ll send them to Atmos for the upgrade. 

AudioTroy thanks for that quick comparison that makes sense to me after owning the Finale Audios 300b’s great amps, but they never left me with the feeling they were doing the speakers justice I had at the time (living voice speakers only 94db, I've since been experimenting with horns). 

I've owned and enjoyed a few ProAc models over the years as well so nice to know they are a good match. (older ones anyway). 

thanks all I've texted my friend and going ahead with the buy. consider me M60's owner. 

Now to decide if to keep my preamp or move to a balanced Pre. I have a completely redon Sansui CA 2000 that has every cap -diode - and various other things replaced. Its surprisingly good sounding now.  Its actually down right amazing now, with so much flexibility I forgot how much I missed some of the things old preamps had). 

But a simple Schiit Freya + may satisfy the balanced proposition on the short term as a reasonable cost alternative. I also have a balanced Schiit multi bit DAC Gumbi and Gold Note PH10 phono stage that's also balanced that may move me to a whole balanced system, well mostly my tuner isn't balanced. 


Cheers all

Glen