There was one observation I forgot to make in my last post to you that I think would, possibly, give you some piece of mind. I cannot speak for all OTLs in general but the Atma amps are designed specifically to address the concerns you have been made aware of regarding the potential harm that could come to a speaker if an amp failure should occur. I don't know if this common practice still but at audio shows, Ralph used to demo his amps by pulling output tubes out of them one after the other while playing music and would even induce a dead short in them (by jumping the + and - speaker terminals) in order to show how composed and unperturbed they were in extreme conditions. No drama, no fireworks, no blown speakers. I think you can rest easy on this count. And in my 25 years of ownership, the worst thing I have experienced is an arcing tube. Never lost a grid resistor, even.

Man, I'd sure like to have a listen to those new GTs you've got coming. What color horns did you go with? Are you trading/keeping/selling the originals? And are you getting Duo or Uno GTs?

As regards the transport upgrade, first let me clarify the error in my first post where I stated that Enco is in Novi, Mi. They are, in fact, located in Oak Park, Mi. A different Enco is, in fact, in Novi. Weird coincidence, I guess.

The upgrade is rather pricey at $1500 euros (at the time of my purchase) but the experience has been good both with the distributor and Dr. Volpe himself. He actually called me from Germany to get feedback from me after I had the unit in use for a couple of months and I felt he was genuinely interested in what I had to say. I wouldn't say the swap job is a suitable undertaking for a complete novice but my tech said it was a piece of cake for him and the assembly was a true drop in replacement. All the possible replacement transports I was looking at were $7500 and up so, having had no failures in 22 years of ownership (including the original drive unit I replaced), I decide to gamble and, thereby, save a pile of coin.

Regarding the Atmas, I bought my M60s, my MP-1 preamp and Duos all within about a year of one another some 25 years ago. Other than the occasional tube, I have had no failures to deal with. The sound is clean, fast, transparent and, most of all, humanly musical. I have never been compelled to look elsewhere. However, I have no quarrel with Gan Fet class D and I know that Ralph Karsten himself has shelved his M60s for his own GanFet amp to be employed driving his Classic Audio Reproduction speakers, claiming that the SS amp is slightly more transparent with a better 3D illumination of the back of the soundstage. But I remain a skeptic. There is something just more right and natural sounding coming from a vacuum tube than any transistor amp of any persuasion in my experience. Find a good source for tubes (which, apparently, you have had trouble doing) and you should be good to go for the long haul. I've had really good luck with 6AS7 pulls purchased on ebay from Russian sellers in lots from 30-100 tubes at a time. My driver and small signal tubes all come from Andy at Vintage Tube Services. He's the real deal. My experience with Chinese tubes of any variety has been universally unsatisfactory. I would avoid.

Is it possible that the fellow in the UK who went to Audions from the S30 Is the guy who modified the Duos to eliminate the three post framework for his (beautiful) custom horn mounts? If not, a chap that, I believe, posts on Audio Asylum and Whats Best Forum under the moniker "now hear this" and has used the Atma class D's on his Duos (he has two pairs of different vintages) would be someone whose opinion on the matter I would value. Anyway, FWIW, I would consider the move to Gan Fets a sideways move with some possible subtle gains in clarity but with a loss of the natural rightness of the vacuum tube signature.

I hope all this helps some. By all means, let us hear about your time with the GTs once things have settled in.