I feel at this level of amplifiers (30 to 50k), Nad, CA and Marantz are all pretty much similar. They all vary slightly in terms of voicing and it depends on what the listener wants.
His question is related to power.
What is better ? More or less ?
Simple question but the answer could be complex. Because ??all watts are not similar?. Technically all ??watts? should be same but it is not. It all depends on the amps and its design.
For example a 25watt class A sugden A21 will have more drive than a 60 watt CA and will not clip at higher volume levels. So if you ask which amp can damage the speakers at high volume levels by clipping ? The CA or Sugden ?
The answer is of course CA. But the CA looks more powerful on paper right ? The truth is that the sugden is a better design with fantastic drive capabilities. It costs four times the CA.
Another example, a 6owatt NAD vs a 150watt NAD. Of course the 60watter will clip faster and fry your tweeters sooner.
So I guess, if you are looking at the same line of amps from the same manufacturer, the higher powered one will give you more dynamics and head-room without clipping than the lower one. But if you compare across lines, the answer may not be so easy because other factors like better power supply, current capabilities and other design parameters may swing in favor of the lower powered amp from a more expensive line.
Common observation is that most people blow their speakers with lower powered amps than with higher powered ones. People generally turn down the volume when it gets deafening. With a high powered amp, at deafening levels there is no clipping so nothing happens to the speaker but the lower powered one will be constantly clipping and can potentially fry the drivers. This is the reason why Nad amps comes with a soft clip switch which you turn on while partying at high volumes..

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