There might be something to this, but many engineers of great new “digital” amps say that the Class D amps have plenty of punch and heft.I also have a GK 700RB and yes the class AB style heads with the heavy transformers that put out a lot of heat seem to have a different delivery, more punch and heft on the notes.
That said, when I used a REDDI I thought (maybe it was all in my head) that there was a feeling of “weight” when I played it. It does have a giant, heavy iron transformer. IDK.
