1st full tube amp Oldchen EL34

Oldchen brand-does that indicate it's run by old guys from the CCP, instead of young, rebellious anti Xi Jinping millennials?

Seriously, if you have access to a legit tech that knows tube amps to point out potential safety concerns, that's maybe to best move. They need a schematic to really know what's going on. I'd see if the company can provide one.

The transformers and quality of the parts, obviously are going to limit just how   much it can be tweaked to sound "better."

That could add up quick.$$

Understood and again this was an opportunity but not a nirvana situation. I have the top of the Line LSA HYBRID that drives my Thiel CS5s and totally pleased. I have a bardominium playground for my grandkids and this is where I like to tinker. Heresy’s, Chorus 1s, and Quartets are the available speakers at this location. I change between Bryston, Mitsubishi, Lexicon, NAD, and other assorted amps. Most I have brought back from dead. And most sound better today than when new due to better parts. Never opened a tube amp and I have a significant amount of respect for the damage they can do if mishandled. Variac on-site and have still smoked some things in the past. 😉

I have run my Quartets with a 4 watt Decware Mini Torii and a 6 watt Grommes PHI-26  both sound great the quartets and tubes makes if sound like a liver performance

The first thing I would do is replace the rectifier tube (assuming it's tube rectified and that the tube is of Chinese manufacture).

A quick Google showed an inexpensive Oldchen single ended EL34 based amp with a 5Z3P/rectifier (2) 6N9P small signal tubes and (2) EL34's (one per channel).

Is this the amp?

A failing rectifier tube can wipe out the EL34's plus other passive parts of the amp which is why I would start by swapping in a known to be reliable tube.

Reasonably priced one's (for 5Z3P) would be a Russian 5C3S (all I've seen were manufactured by Svetlana) or a GE 5U4G (both run around $30, while other brands start @ $100+).

That done I would just listen to it for 3+ months before changing anything else.

The 6N9P signal tubes are equivalent to 6SL7 (not familiar with current prices and/or what people like for this tube).

I'm not Anti-Chinese tube on a whole as I've heard some of their EL34's, 2A3's, 300B's and 12ax7's that sound quite good, but their rectifier tubes seem to have a bad rep for reliability.

Before you start tinkering inside learn how to safely discharge the power supply capacitors.

DeKay

Thanks DeKay. I have worked with capacitors in ss amps so I understand the need to discharge for safety. I will order the rectifier and see what happens. I believe this is the same amp. May have also been labeled Laochen on other units.