Not being an amp designer or even an electrical engineer, my expertise about this is next to nil, but, after reading a lot about amps and their designs over the years, I learned one thing: there are very few universal rules when it comes to amp designs... especially today.
Amplifier feedback done wrong, like anything done poorly, sucks. In audio and physics, there is no free lunch. But, then again, what happens when you discover something new?
Negative feedback was overdone by amps in the late 70's just to get low THD specs. That had some severe drawbacks in those types of amps. Then Bruno Putzeys came up with his stuff and found a way to use a ton of negative feedback in his class D amps to fantastic effect.
THX and John Siau of Benchmark came up with with the achromatic (AAA) AHB-2 amp design that uses parts of class A, B and D design for what seems to be a new topology. It uses a feedforward correction scheme and it's one of, if not the, best amplifiers ever. It also uses a switching power supply which, common wisdom dictates, is supposed to be for cheap, mediocre equipment. The PSU, though, is so good that I was told by their head of sales that hooking the amp up directly to the wall is suggested and that, in the off chance of a catastrophic voltage spike such as lightning, the amp should be fine.
The best thing about all of what I mentioned is that it's been independently verified (not the AHB-2 lightning strike, sorry). This isn't supposition, hype or snake oil.
So, my thought is this: I don't care about the technology as long as it's proven to work.
By the way, love the photo of the old Marantz receiver at the top of the article.
