WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
Building, troubleshooting and testing of these amplifiers should only be
performed by someone who is thoroughly familiar with
the safety precautions around high voltages.
Just been milling over your suggestions, and it seems a whole lot better than what I started with! PSU ripple, as said, has been greatly decreased!
Cheers again! Who says you don't learn new things every day, and having fun while you're at it!