Absolutely agree with you Microstrip. I work on equipment myself (Electrical Engineer, with Amplifier design background) and have modified many amps over the years. Thresholds are the best to modify, Bedini's (great amps) and easy to modify, even Robertson's. The pre-drivers and output drivers are outdated and not as linear as the newer better drivers. The power supplies can be upgrades into duo power supplies and wow! My modified Bedini 250/250 Mk II blows most $3,000-$5,000 amps away. Seriously. Interesting output design. Inverted push-pull or sort of a pull-pull. Totally eliminates having to match NPN and PNP output drivers and you only need NPN's. I will look into the 23.5 and see if any leakage is occuring and see how much the large electrolytics caps would be to replace.
enjoy
enjoy