Reviews on JungSon amp/preamp combo: JA-1/JA-99C

But 20 years younger and dumber I decided to hope for the best.

I guess many of us fell into this trap.
In my case, it's not been that bad.
I've purchased one integrated tube amp (Yaqin MC10L, $550) and tube preamp/phono (Yaqin MS12B, $250) directly from China over 10 years ago. I played around with different tubes and it was fun to notice the difference of sound from different tubes. I also played around with bias adjusting after changing tubes each time, and I blew up few resistors and replaced them by myself, ... on MC10L. It sound pretty good overall, but I eventually sold it.
I don't use the preamp but I still have it. It sounds OK for under $300.
I see they are still sold new at around $1000 and $400. At least these two models did not seem to have as many problems as you had with what you bought from China. 
From reading online reviews, JungSon appeared to me to be at least as good as Yaqin in sound and build quality, and that's why I'd like to hear about them from Agon users. 
It appears that most of Agoners either have no experience on them, or just are not interested in talking about this Chinese brand, or any products from China.

My Plinius SA102 eventually died (due to my stupid mistake) and I needed a new (temporary) amp. I have a few spare amps (Nakamichi, Mitsubishi, and AR) but they are far inferior to Plinius.
Against millercarbon’s horrible experience with Jungson, I made a plunge and bought them. It took a less than a week to get to Michigan from China. Well, Jungson exceeded my expectation. I cannot say it is better than Plinius, but it is certainly better than my old Japanese amps and quite close to AR 150M.2 which cost 4 times more than Jungson 20 years ago.
My AR will go to eBay soon.
The preamp JA-1 is also very good, but certainly it has its limit compared to my other preamps (Plinuius M16 and PrimaLuna Diaglogue).
Jungson JA99C is rated as 80wpc class A, but it sounds as loud as 125wpc class A Plinius. I am not a big fan of Chinese audio products, but I cannot but give a big thumb up to Jungson amp. Hope its reliability is as good as its sound.
It will take a while to service my Plinius, but since then I will certainly enjoy Jungson. After I get Plinius serviced, Jungson will work in my second setup.

Have a 200 watt integrated that is nice but has developed a slight hum, very difficult to find a repair person that can take on a supposed Class A transistor device with no access to a schematic or manual.

Have you contacted the seller? Well, many Chinese sellers don’t stay in business long to take care of after service, so you may be out of luck. That’s I’m worrying about too. When I addressed the possible repair situation to the seller (Mr. Yong Lee), he said I can send my amp to their service center in US.
I hope no such occasion occur in the near future. Even though you might not have bought yours from Yong Lee, you can still ask him about their repair center in US. His email is admin@china-hifi-audio.com.

If you do get a hold of him, ask why he came to my house looked me in the eye and lied straight to my face. Ask him why Stewart had to make good on his crappy amp because Jungson wouldn't honor their warranty. I would ask him myself but once someone has proven to me their word is worthless what is the point? Do you get the idea how I feel about Jungson? Best of luck to you, anyone fool enough to do business with them.