Interesting mind set of the guy that rebuilt it. He added a choke for the input sections which is a good and logical move. But then he bypassed all the coupling caps with what looks like polystyrenes. Doubtful if those made any difference. This is all just tinkering around with the existing circuit, and the original circuit could have been done better with better capacitors like AudioNote Kaisei electrolytics for the cathode bypasses and FT-2 0.1uF teflon coupling caps. They're rated 200V but in practice being military stock are OK for over 300V. You really need DC Link caps for the PSU caps and they do exist in round versions, the usual versions being rectangular.
But you could take a radical step and use a different circuit entirely. I'm doing that with my own Stereo 20. The EL84s are in triode, no global feedback, and the input valve is a choice of 37 or 76. Those old 5 pin valves sound marvellous. Way better than all the 9 pin valves that are used in commercial circuits. I'm using a mosfet phase splitter which is a space-saving way to do it and by all accounts sounds very good. I haven't tried that before and just coming to it in my build. The output section is up and working, with a choke in the PSU made up of 2x 8uF, 100mA chokes in parallel, the old Maplins ones like in the circuit in the original post. When it's all built and working I'll post details.
I'm not much of a guy for cosmetics - I leave that to others. I really enjoy designing and building valve circuits, so that's where the motivation lies for me.
