Speakers for Atma Sphere M60 mk3

@fredag Your room is a bit on the larger side. If I were you I'd be wanting to see if an audition could be arranged.

@fredag How much power are you running right now?

@fredag For the M-60s I would use speakers that are at least 8 Ohms and 91 or higher efficiency.

With any amplifier, tube or solid state, its beneficial for the speaker to be easier to driver rather than harder; this will always result in less distortion! The higher impedance speakers will also be less critical of the speaker cables.

I would expect the class D to work fine with the Elipsas, depending on the size of your room and how lively it is.

The problem is that many can fix the amps but they do not have access to parts from Harman. Now: can I buy parts from YOU, IF needed? Living in the frozen north is a pain....specially without music ;)

@fredag I get that- we live in the frozen north too! Our amps are designed not only to be easy to service, but to also work with available parts. You can certainly get them from us! We stand behind our products even if they are decades old, although when we service our older products, they are likely to sound better than when new...

@fredag Somehow we've managed to keep our products alive in Europe :) We've been exporting to Europe for the last 33 years. They about built to last and also to be easily serviced.

The SF is a 4 Ohm load, rated 91 dB Sensitivity. To convert to Efficiency, which is a more useful spec for tube amplifiers, you have to subtract 3dB on account of the fact that Sensitivity is a voltage measurement, while Efficiency is power. 2.83 Volts into 4 Ohms is 2 Watts and the Efficiency spec is 1 Watt/1 meter. Thus we arrive at 89 dB.

I don't think the M-60 can make enough  power in a room of that size, even when using the ZERO autoformers to correct for the impedance (and also results in more power, about 80 W/channel).

IME, having used speakers of that efficiency in a room of similar size, I found 200 Watts to be more satisfying. You have several options; if you get the M-60s and keep the SF loudspeakers, you want a set of ZEROs and you'll be living with occasionally overloading the amps.

Or you could get a more efficient loudspeaker. Some good suggestions are on this thread (I don't think the older Quads would be good since they are not all that efficient).

Or you could get an amp with more power for the SFs. If you go this route, FWIW our class D amplifier sounds a lot like our M-60s and has no problem driving 4 Ohms with considerably more power.