Review: Green Mountain Audio Eos vs Callisto Monitor

Category: Speakers

I took advantage of an opportunity to upgrade my Callistos to the newer (and more expensive) GMA EOS. After spending more than a year with my Callistos and enjoying every minute, I felt some reluctance letting them go. It was a bit difficult for me to think that the EOS would be a big improvement over these very enjoyable speakers. I was in for a shock. Roy had explained the differences and actually painted a very realistic, if somewhat downplayed version of what I should expect from the EOS.

I spent a good deal of time reviewing my favorite music before the Callistos were sold. I was really ready to miss them. When the EOS arrived and I hooked them up, I was blown away. I plugged them in to the exact system and position as the Callistos. Roy even advised that I would not need to re-adjust my subwoofer settings, since the sensitivity and response were so similar. I run flac files through J-River using Ayre equipment. I have a large selection of Redbook and a fair amount of 24 bit recordings with a few 24/192 selections. All of the qualities I liked about the Callistos were still present but with noticeable improvement across the complete spectrum. Whereas the Callistos disappeared in the room, the EOS floated the music in three dimensional space and transported me into the performance. One of my favorite recordings is a Channel Classics recording of Rachel Podger playing the Bach violin Sonatas and Partitas. As soon as the mic came on, I could feel the presence of Rachel in the recording booth and sensed the space around her. The position and clarity of instruments is pretty amazing. Guitars and piano sound incredibly realistic and exist in space exactly where you would expect them. On “The Last Recording” by Horowitz, the position of the piano and microphone are clearly discernible and at the appropriate height. I would not have believed the difference in these speakers unless I had heard it.

One of the improvements that surprised me the most is the quality of bass with the speakers. As an ex-professional bassist, bass quality is obviously pretty important to me. Roy explained the differences in the ports so that I anticipated some minor improvement. The EOS really deliver a much richer and punchier bass that the Callistos. String bass sounds more even and articulated throughout the entire range of the instrument. The other huge improvement came about because of the design of the tweeter. The ability to move the tweeter to set the time alignment allowed me to adjust the sound to my listening position in a precise way. The Callistos did not provide the same precision. Having the tweeters adjusted exactly allows vocals to be incredibly clear and distinct enhancing the three dimensional quality of the music. Nearly every recording I listened to sounds more distinct and brings up the clichéd report that I am hearing new detail in all of my music, maybe a cliché, but true. I feel like a kid in a candy shop, going through every recording and hearing them all for the first time again. It is hard for me to pull myself away from listening.

Roy achieved something pretty special with the EOS. The ability of these speakers to transport you into the performance is uncanny. If you have enjoyed your Callistos but are ready for an upgrade, I highly recommend the EOS. He also claims the HD version is even better. Hmmm, maybe I should get the HD’s? . . . (to be continued).

Associated gear
J-River on Windows 7
Ayre QB-9, AX-7
It never looks good when you post a review of an item you are selling, but good luck. I know that they are supposed to be great speakers.
I only buy GMA speakers and have owned Europas, Callistos and EOS - My goal was to the inform owners of older models how much I enjoyed upgrading to the EOS. Thanks for your feedback.
Why don't you just send them back to GMA for an update? It seems like you're losing an awful lot of money selling them to buy the HDs. I've always heard good things aobut GMA and Roy. I would think he'd be willing to update them for you, and for a lot less than the loss of selling them, even if it ends up being more than if you had obught the HDs to begin with.
I got a pair of Europas via Audiogon, great monitor for the price and eventually I'll upgrade. Are the Callistos or EOS a big step up in performance?
I went from Europas to Callistos and then to EOS. Each has been a step up in performance (and cost). The Callistos provide a big improvement in bass over the Europas. In my opinion, the EOS were a big step up over the Callistos as described in the review. I was actually surprised at the difference. Whichever you decide to jump to, you will enjoy it. If you can afford the EOS or EOS HD, that would be my suggestion. I realize though that you can disqualify my advice since I am selling a pair to go the HD's. They are all great speakers and provide a great listening experience. enjoy them.
My EOS are no longer for sale, same advice! - Roy has agreed to upgrade them (apparently he doesn't like to do this because it is not cost effective and destroys a lot of useful parts). I will them for a few more weeks and will acclimate to them so I can report on the difference between the EOS and the HD versions.
Congrats!!! It seems to make sense for you; you'd probably have lost a lot more on selling and buying new than upgrading. I suppose it is a shame to waste good parts, but compared to the vast quantities of stuff we as a society throw away, a few capacitors or inductors, or even the entire pair of speakers, are a drop in the ocean. I've never heard a pair of GMA speakers, but would like to because people who like speakres I have liked (Spicas especially) seem to like them.
You should give them a listen then for sure - you are welcome to come hear mine if you are in the bay area. I understand this is a subjective experience, but for my ears, they are the most accurate and true to instrument timbre and timing. Like most of us on agon, I have listened to and owned a lot of speakers.
Just wanted to update this review - I received my upgraded EOS back from Roy. He was so great about all of it, helped with shipping, called me regularly to update me, etc. It was worth it just to interact with him.

So how do the EOS HD sound? Well, I could use all those terms that show up in every review, soundstage, transparency, clarity, etc. I am going to skip to what is really important. These speakers make music. Whatever the other qualities, the sound is captivating and emotionally moving. I have played these for everyone who will listen and the responses have been amazing. Two people have cried, one guy would not get out of my chair and just sat there with his eyes closed for 1/2 an hour. Another woman just started dancing around the room with a big smile on her face.

Although I have not listened to every speaker out there, I have listened to and owned a few EOS HD's paired with the Ayre components are the most faithfully musical system I have heard. Instrument timbre is true, timing is impeccable and bass is tight and realistic. The best part is the human voice though. I don't care what your opinion is about time-coherent speakers, when the tweeters and speaker position is dialed in, the voices just float in the room as thought the singer is right in front of you. It is especially nice to hear individual voices and positions when backup singers are in the mix.

For the past 5 years, I have been juggling amps and speakers and DACS trying to achieve this feeling about the music. Now I can sit back and enjoy.
"Two people have cried, one guy would not get out of my chair and just sat there with his eyes closed for 1/2 an hour. Another woman just started dancing around the room with a big smile on her face."

Now that perfectly describes my family room on the rare occasion that I turn off my audio system.

Seriously, an excellent review. A friend has similar experiences with GMA Calypso HD.
OK, that is really funny! Seriously made me laugh.

Thanks - by the way, that is quite a system you have, you clearly have put a lot of thought, time and energy into (as well as cash I guess). No wonder you never turn it off.

Too bad we can't teleport around and hear all these different systems.

I would love to hear your system, but I am just about as far away as i can be and still be in the country (unless you mean the Massachusetts bay area). There is definitely something about time coherent speakers - I now have a pair of Ascendo ZF3s that I think will stop my esarch for speakers for a long time (although I would still like to ehar the GMAs).

Congrats on the new upgrade. I love my C3 HDs. I heard non HDs in a friends system, but hard to tell what the differences are unless you can hear them side by side. All I know is I am extremely happy with my pair. Roy is a genius who doesn't get enough exposure or credit.

Oh, and who's the little guy standing behind the speaker?
I have the EOS HD. For a couple years now. Haven't looked at any other speakers since. Great speakers and allowed me to finally sell off a bunch of others.

Very easy speakers on amps. I run Art 845s, EAR 534s(Aesthetix pre) with no problems. Also have some SS around but been tubes for a while now.

I think a friend summed it up best one day, he said, you put on a different disk and it's like a totally different set of speakers.
I think the little guy on the subwoofer is some kind of fertility god - not doing me much good if I just sit here listening to music!

I really like my Ayre but also have been wanting to try tube amps sometime - I am on a budget though so maybe in the future. For right now, I still have a bunch of music to go through and according to Roy, the speakers will get better once the new CAPS break in - hard to imagine them getting much better!