I bought a Chinese tube amp (Music Angel XD-800 MkIII) about 12 years ago just to play around with upgrading it. IIRC, it was around $500.
When I received it, I opened it up. It looked like the tech who assembled it, just put in whatever parts he had handy on his bench. Most resistors were out of spec.
Once I changed the resistors and caps, it was a pretty decent 30W Class A amp. The tube complement was 4 x KT88, 2 x 12AU7, and 2 x 12AT7. I ran Psvane KT88 and 12AU7 tubes and 50's era RCA 12AT7.
Not including tubes, the upgrade cost me just under $200 (and many hours of my time).
When I received it, I opened it up. It looked like the tech who assembled it, just put in whatever parts he had handy on his bench. Most resistors were out of spec.
Once I changed the resistors and caps, it was a pretty decent 30W Class A amp. The tube complement was 4 x KT88, 2 x 12AU7, and 2 x 12AT7. I ran Psvane KT88 and 12AU7 tubes and 50's era RCA 12AT7.
Not including tubes, the upgrade cost me just under $200 (and many hours of my time).