Sorry,I was referring to actual sonic performance,not smaller size,lower heat,lighter weight.
1. SMPS is regulated while traditional linear PS isn't. Likely to hold voltage better at loud passages.
2. Current pulse response is faster unless linear supply has expensive slit foil (non-inductive) capacitors etc.
3. Higher switching frequency is easier to filter out than 120Hz.
4. 2" torroidal transformer at 100kHz can carry as much power as huge 10" dia toroidal at 60Hz. This allows to build stronger oversized supplies (within the same space and cost).
As for "NOT talking about class D design" - it's the same thing (class D is adjustable SMPS).
Please notice I don't praise size or efficiency of SMPS but every design has cost and size limitations. To talk about advantage of SMPS - we have to refer to performance achievable within the same size and cost as traditional linear PS.
Shadorne, you're right - they might produce EM/RF. Everything is in the hands of designer (and layout designers).
I was trying to show best case advantages od SMPS. Unforunately companies often use SMPS topology only to reduce cost making often worse (weaker and noisier) power supplies than standard linear ones.
Layout of SMPS supplies is not trivial and requires detailed knowledge of the operation of the controller IC(current flows) not available to PC Board designer.