NOTE: This was my first post tonight that vanished completely. I basically somehow deleted it. I had to start over from scratch so I wrote the post above as my second draft. Then after I posted it, this my first post appeared. I am going to leave this one up too so you can have both versions.
UPDATE MAY 9 2022
Probably the biggest change of late is moving the amp to the house speakers for the final voicing. They are very different from the ZF15L and HDT where I started.
They have uncanny imaging focus. It’s really tight, like to a pin point. And because of that and their overall balance I had an interesting experience that I know I spoke about somewhere on these forums.
I had resurrected a TORII MK5 prototype from years past that never made the grade. I finished it and in the process created a one-off design that I still kind of wish I had kept. The reason was because I had hooked it up to the house speakers and it had this relaxed, deep sound that was the best I had heard in many ways on those speakers. In fact I had the amp duplicated as close as possible. The only change was the power transformer, and even after matching the voltages it became sadly obvious that it was still enough of a change to never quite capture that sound. A sound I can still remember, like a ghost that haunts me.
So with this back story, I am presently working on frequency balance and imaging / soundstage.
I have installed 3 temporary switches on the amp that let me hear A B C configurations. A is my original configuration that I thought was it. B is bypassed completely and C is my new configuration that I think is it.
We can no longer reference the ZROCK2 with regards to any further voicing including these switches I am using to find the perfect setting. This is because the circuit is getting bent in a way that can’t be done with the ZROCK2. It is getting bent to compensate for the signature of the WE300B so that final sound is closer to our other amplifiers, which is to say a bit more neutral.
The two main settings are a humbling reminder of how bad bypass sucks. It sucks only from the perspective of getting the sound stage shoved a bit forward from the back compressing the depth and adding a touch of hardness that shouldn’t be there. Again, a sound I have often blamed on the recordings. Setting A is really good, measuring ultra close to flat. Setting B has a very tiny smile. The midrange is dished by around a dB, the top end is not and the bass is up by about a dB. This unrolls both ends of the 300B and makes it sound a little more like our other amps.
Last night I took the amp in the listening room and started in setting A which I was used to. I then compared it with bypassed and bypassed isn’t quite as bad as catching your pecker in the zipper but it was pretty rude nonetheless. Then I went back to A for another hour. Then I switched it to B and it was a holy crap moment because I got that same amazing, like twice as good, soundstage that I have only heard once before…
When I say twice as good, I mean four times as good. It was like getting all the mirrors aligned on the James Webb Telescope.
Tonight I am focusing on B and it was going great until I played Daft Punk and the low bass drew attention to itself. I half expected that, but that bass is needed in the signal to align everything in the driver stages, so rather than go back to setting A I have reduced the coupling caps feeding the 300B to dry clean the sound a bit by preventing exaggerated low bass.
The textural depth is paralleling the sound stage depth. One requires the other and both require a room that allows it to happen and it is happening big time under these reference conditions.

click to enlargeI have also been working on the final chassis layout as I continue to polish this. Tonights cap is 10x smaller and faster with less thickness through the middle. I suspect I will probably end up in the middle before it’s over.
The take away, is the sound stage and clarity of all the layers is twice as good as anything you’ve heard in the videos so far, not that you can even hear that in the videos which is why I don’t mind saying the amp is completed in the videos when in reality it is still improving for those with the reference environment for it to express itself.
It just blows my mind how huge and fundamental the change is, and it’s only 1 resistor’s value that is controlling this whole thing. I have the amp so dialed in that it’s like a race engine where changing the timing by only a couple degrees can bring everything together to win the race.
The notes get deeper. Instead of a note being a bubble of sound, it has become a highly defined bundle of textures that combine to create the illusion of a note.
You don’t hear this deep into stuff with most audio gear. And from the 300B sound I started with as you may remember I wasn’t confident it was even possible with this amp.