Massive power supplies help. How much does the Manley weight vs the Cambridge?
Also, when you look at specs, you will see dynamic headroom. Some amps can put out peaks anywhere from 0db to 3db to 6db or more. What that means is that some amps rated at 32 watts will sound lousy as soon as they try to push 33 watts, while other amps with let's say 3db of dynamic headroom can handle 64 watt peaks without any noticeable loss of sound quality. Many times you are only playing at 5 watts but may need 10 times that for peaks in the music.
Also, when you look at specs, you will see dynamic headroom. Some amps can put out peaks anywhere from 0db to 3db to 6db or more. What that means is that some amps rated at 32 watts will sound lousy as soon as they try to push 33 watts, while other amps with let's say 3db of dynamic headroom can handle 64 watt peaks without any noticeable loss of sound quality. Many times you are only playing at 5 watts but may need 10 times that for peaks in the music.