Figured I'd share my progress on my own amp builds as I work on my NX-Oticas as well. Last fall, I started a pair of Folsom EC7293 monoblocks, and back in January I bought a Elekit TU-8600S to assemble at some point since I had so much fun building a TU-8800.
Last weekend, I finally had time to start the 8600 build, and I did it over three evenings: the soldering split over two and the transformers and case the third night. It came alive immediately with no issues, and I can already tell it sounds amazing with just the Gold Lion 300Bs in it - I'll try a few other 300B tubes at some point, but for now this will do. The kit came with all the upgrades, and I added VCaps as well.
After that experience, I really wanted to finish my EC7293 builds, which had been mostly done minus final assembly and waiting on a few parts which had since come in. Like others, I decided to include the Neurochrome slow start boards, and also have a set of the speaker protection boards that I might integrate in later. For now, each amp will look like this:
I saw "will" because it was a bit of a mixed bag. The first one fired up just fine, and I initially tweaked it to have a 8mv DC offset. A little later I went back and was able to get it down to as close to 0 as I could (my meter will flash 1mv every 30 seconds or so).
I was not so lucky with the second unit. First, it had a .4v offset at the output jacks, and the photocells were only reading 2v with the light module. They read a full 8v with my LED flashlight, and the offset remained even if I used the flashlight on the PV cells. I also saw a .3v potential across the input with nothing attached, which seemed odd. As part of an experiment, I plugged a cable (with no signal) into the RCA jack to see what would happen and -poof- I had a smoking 7293 and a blown fuse! (Sorry, no pictures.) Upon disassembly I discovered that one transistor leg had popped off the solder pad and was hovering less than 1mm above the pad - impossible to see with the board installed against the heatsink. Probably happened somewhere between the drive from my workshop and back, or in the months it's been sitting waiting to be assembled.
I've already fixed both the transistor and replaced the LED module, but of course the EC7293s are on backorder now, so in the meantime I have a really nice sounding monoblock. I still need to drill out a hole on the faceplate for the power switch, which I installed on a long enough wiring harness to fit wherever I finally decide to put it.