Vincent wrote:Does the quality of an amp vary according to where it's made? ie; China,South Korea,Vietnam ?
No. Electronic circuitry doesn't know what country it is being made in, or who is making it.
Provided that the components are of sufficient quality, that they are of the right specifications and tolerance and provided that the implementation (quality of physical design and workmanship) is of sufficiently high quality, a given circuit will operate in the same way no matter where it is made.
Quality is the key factor. Cheap amps are usually designed down to a price. Take Fender amps as an example of the higher end. For the premium handwired reissues and custom models (typically costing £1500 to £2000 for a reasonably high-powered valve combo), the components will be the best the factory can source, and preferably equal to or better than the vintage components used 40-50 years ago. Then there are the valve "reissues" built using PCBs (I have two of them), costing sort of £900 - £1250 depending on model. These, apart from the reduction in cost afforded by the elimination of handwiring, still use best-available premium components, especially the transformers and the speaker(s).
On the other hand (and passing over the company's USA-made all-solid-state amps), they do a range down at the bottom end (eg, a 100w two speaker combo for around £200) which are perfectly fine for many purposes, but which achieve their price point by ruthless cost-cutting and cost-paring. Key components such as speaker and transformers are sourced very cheaply and you don't get good robustness and longevity (electrical or mechanical) at those sort of prices. Then there's the effect on the audio-chain.
The main point is that volume is not just a function of power output. All the links in the chain need to be strong. A 50watt amplifier with good transformers and speakers can outperform a 100watt amp with low-quality transformers and speakers.
JN