And who can clarify what I read about the weight of pre/amp in the quality of the final sound.
Unless it is a topic about one's fantasies with trolls, laws and psychological analysis.
With a "linear" power supply (ie a transformer, and then regulation circuits and capacitors) - the capacity of the power supply is directly proportional to the weight of the transformer.... and as the power supply ultimately defines the limitations of any amp, weight is a good sign for a traditional "old style" amp...
Additionally, traditional amps have lots of transistors that get hot, and require large (heavy) heatsinks to cool them - lighter heatsinks have less thermal mass... they can work too, but usually in conjunction with a fan, which adds the potential for audible noise, as well as fan generated electrical interference.
Then switching power supplies came along - and they broke the whole mass=power paradigm.... the weight of a switching power supply bears no relationship to its power output capacity.
So now you have pro heavy duty power amps with 500W + outputs, that can weight several kg... where a traditional amp of that output would probably weigh 30kg+
Class D amps are also extremely efficient, and require little or no heatsinking to provide substantial output power - so there is little or no need for heavy cases with solid heatsinks ...
In the modern world you can have:
Traditional Class A/ AB or similar (Class G/H, FeedForward/Currentdumping, etc...) - with linear power supply - HEAVY
Traditional Class A/ AB or similar (Class G/H, FeedForward/Currentdumping, etc...) - with switching power supply - Mid weight (big heatsinks)
Class D with Linear Power supply - Mid to Heavy (still has big transformer, but doesn't need big heatsinks)
Class D with Switching Power supply - Light (500W stereo amps at circa 5kg!)
So if you are looking at a traditional design with a traditional power supply, and it is light weight - you should indeed look on it with some suspicion!!
Similarly a ClassD amp with a switching power supply that is heavy, the heavy case is most likely primarily "Bling" - and serves no useful purpose (or if the heatsinks are properly connected/mounted, then it may server a marginal purpose)
And Yes - there are mix/match designs that sit in the middle, just to confuse the unwary