Raul, the EA-230 is the older Berning design, which used traditional output transformers. I am referring to the new ZOTL designs which are completely different than the EA-230 was. My amplifier is a ZOTL design.
It is still not "perfect" for all speaker types, but it is a very large step in the right direction for tube amplifiers, when used with the a correctly matched speaker system.
It is my estimation, that this concern of yours which we are discussing, is primarily related to speaker systems which have wide impedance swings into lower impedances that would have negative effects on tube amps with higher output impedances, and on that I agree with you.
However, one parameter does not make an amplifier, and there are speakers for use with these amps which will keep the frequency response/output impedance curves at a level within good acceptable ranges for music listening. While many SS amps do have the very low output impedances that would work well with difficult speakers, that parameter alone does not make them good for musical listening. As you well know, there are other things involved with this.
I am not trying to change the "physics laws". What I am doing is pointing out that a variety of tube amplifiers when used with properly matched speaker systems, can have acceptably flat response curves(even if not perfect), and still provide a very musical result because of other strengths that tube amps have and other weaknesses that SS amps have. I have been primarily on the "defensive" side in this argument, because I don't wish to insult people that use SS amps. But I will say that some of the more expensive and flattest response SS amplifiers that I've heard provided some of the worst listening experiences that I've ever heard. They don't provide specs for "grainy, hard, or cold" sounds. People don't call them "sand amps" for no reason. However, I will admit that some good SS amp designs do provide a very flat response and a tonal quality and overall sound quality that can come close to a good tube amp. Basically, you can "pick your poison", nothing is perfect, and you buy what you like.
What I chose was a carefully selected blend of Single-ended Triode coherence and tone, with similar speed and control of SS(using the ZOTL impedance converter), and the open and transparent sound of OTL. I had David Berning himself design and build it with his own hands. It is the only one of its kind in the world. I selected speakers that would work well with it. It makes music. It is the only item in my system which is not replaceable. I call it "The Holy Grail", because prior to the Berning impedance converter invention, it was simply not possible to have an amplifier with only one output triode per channel in a single-ended triode configuration, with no output transformer, and achieve anywhere near a low enough output impedance to operate any normal speaker. This amp not only achieves a low enough output impedance, but puts it closer to what an SS amp might be(without feedback). In my opinion, this amp is the cutting edge of audiophile amplifier design, going where no amp has ever gone before. Using a single Type 45 output triode to directly drive a speaker element. This is a revolution in amplifier design, because it takes the best aspects of best tube design(SET) and provides a solution for what previously were the drawbacks of the no-longer-necessary output transformers, and provides better impedance matching, and direct drive from the triode. The result is "top to bottom" freqency extension capable of square-wave reproduction anywhere in the audio range, blazing speed, transparency, openness, tone to burn, superb coherence due to the pure Class A design inherent in SET, super short signal path, ultra low-noise due to RF tube heaters and no AC power "grunge" due to rechargeable 12vdc battery power, improved linearity due to choke loading, incredible grain-free liquidity and a musical sound quality overall that is "to die for".
Now if I have to "settle" for a fraction of a db of frequency response variation at a couple of frequencies where my speakers are a bit reactive, in order to get all these benefits, then that's fine with me because I got the better end of the deal.
