People need to be aware that the Sugden class A amps have higher output impedance /lower damping factor than most SS amps.They are medium for these traits wheraes most SS amps have low output impedance and high damping.So electrically they operate more like a push pull tube amp.To sound their best they need to be matched with speakers that do not dip too low in impedance-genuine 8 ohm speakers rather than 4 ohm.They are an especially good match with classic BBC and Tannoy speakers that tend to be higher impedance and which can sound overdamped by most SS amps.So when some people say they sound really good and others not so good that is probably just a reflection of speaker matching variables.Given the right speakers they can sound fantastic.