I don't know a lot about amp construction etc but I have a question about the Marshall,
I have read the tubes are mounted directly to the PCB and this is not really ideal, coupled with Marshall's sometimes questionable build quality, do you have any concerns about the reliability of the amp ?
Most amps these days have valves mounted on the PCB.
To use chassis mounted valves sockets requires that they are wired by hand, which will significantly increases the production cost of the amp (assuming you can find enough people with the requiste skills to hand wire the sockets).
The 2 main issues with PCB mounted sockets are broken solder joints due to mechanical disturbance when valves are replaced, and collateral damge to the PCB if a power valve shorts.
Power valve shorts in this amp should be eliminated by the active bias/ power supply management in this amp.
Although some of Marshall's recent products haven't been that well executed to say the least, they have an excellent service department and give very good technical support.
