Ehein324, since you have Eidolons, I'd encourage you to consider whether you can step up to a pair of used Atma-Sphere MA-1 amplifiers. In my opinion, there's not much out there that will be able to match the results you'll obtain with that combination of speaker and amp. It will vastly exceed what you're hearing today.
Hi Wireless, thanks for your kind comment. I agree with Pubul57 that the Merlins are a good match, although the MA-1 with a bit more power is an even better match with the Merlins. The Merlins continue to be a favorite speaker for me, after the Eidolon. The Merlins do so much so incredibly well.
To answer your specific question about speakers that will match well to the M-60, the thing to watch for is a smooth impedance curve of 8 ohms or greater, with no big dips. The Merlins are a good impedance load, and they will sound really good with an M-60 (as Pubul57 says), but in my experience the Merlins will really shine if you can give them a bit more power. Other good matches for Atma-Sphere m-60s include Coincident, early Quads, Spendor, Harbeth (a bit low sensitivity however), Talon, Vandersteen, most horn speakers, and I'm sure others. Look for 8 ohms or above nominal impedance with minimum impedance of 6 ohms or greater, and 89db or greater sensitivity. These parameters are likely to give a good match to the M-60.
Many people will recommend the Zero autoformer as an after-market addition to ameliorate the impedance issue, but I find one loses transparency with them.
