Atma-Sphere S-30 / GMA Callisto / Speltz Zeros

So, I've spent the last couple months swapping all sorts of goodies in and out of my system - some beneficial, some not so much - but it's all been enjoyable and I�ve learned quite a bit along the way. One piece of gear that made an immediate impression, and continues to do so every time I turn it on, is my Atma-sphere S-30 amp.

I�m happy to say that I'm stunned - absolutely stunned - by what the S-30 did for my system. With the lights dimmed and a good recording on, I swear I can get up off the couch and walk between the performers. The sound is whole, organic... visceral. I�m done buying amps, that is until I have room for larger atma-sphere monos!

I am a bit perplexed by one thing - when swapping a set of Zero Auotformers in or out of my system (speakers are 4.8 ohm / 90 db GMA Callistos) I couldn't really tell any difference. I figured the Zeros would be an absolute necessity given the 4.8 ohm rating of my speakers, however, I've found this not to be the case.

Just wondering if any of you have paired an S-30 with Green Mountain Audio Callistos, and if you found that Zero Auotformers were or were not necessary.

I�d be remiss if I didn�t say that if you're curious about tube amps and haven't heard his stuff, give Ralph's goods a listen - I promise they are worth the drive. Speaking of, Ralph, Adam, and the rest of the guys at Atma-Sphere are some of the finest you'll ever work with. They have a commitment to and passion for their products that is all too rare these days.

I have no affiliation, just a satisfied (though that's hardly a strong enough word) customer passing along my experience.