I do know why it is necessary for anybody tell you anything – use your own judgment. Leaving aside the advantages and disadvantages of transformer coupling use you own common sense to think about the bandwidth of the transformers loaded with series magnetics. We are all agree that SET amp with output transformer have challenge with bandwidth. Better lower end is problematic for high end and vice versa. So, a mandatory output transformer from a perspective bandwidth might be viewed as a band-path filter. Now, we have not one output transformer but input transformer, coupling transformers or a series of band-path filters, which makes the band-path of very high order. Surely the input transformers and coupling transformers is much easier to make wide bandwidth but then the phase shifts at HF begin to bubble up and a few other things… Ok let me I will give you an interesting lead: did anybody pay attention that all coupling transformers-loaded amplifiers (among those that I heard) sound in a similar way as the amps with high voltage output tube that run over 1KV on plate. Did you ever think why?
Anyhow, I under no circumstances would like people to have this post as some kind of anti-coupling transformers post. There is nothing wrong with transformers coupling. But in anything shell be a reasonable sense. Yes, “some” transformer might “improve” sound and there are even freaks that put after bad SS amps a good 1:1 transformer to cure the SS nastiness. However, I do see a lot of “sense” in Sakuma-style transformers using. I refuse to accept not the topological the circuitry decisions but the actual sound that I heard via those amps. Was it due to the transformers or due to many other things that Sakuma did? I have no idea. However, it was very huge disassociation between the BS that was spreading about him, my expectation and the actual not even sound but rather the way how he was trying to get sound. There was something extremely sloppy in what he did. It was kind of almost “as is” or accidental sound, in addition to be very poor sound and I did not recognize a lot of thoughts behind this sound.
I do not know why I was bitching about it. Most of the people are getting home accidental sound and when I witness it I do not complain – I know that they are accidental people in audio. Sakuma, however, was sold to me differently and I properly do not feel good about my stupid gullibility…
"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche