Oscars review....from '08 points out the use of the ASC module, which I believe needs a powersupply. OR can be driven by the appropriate power rail on an ASP module.
'd' may lack upper range information on very low impedance loads where the Zobel begins to drop off the frequency response.
Also, at least from the visual standpoint, the W4S amp is the back panel DUPLICATE of my PSAudio GCC series. The so-called 'gain cell' input on the PSAudio? Who knows? It could be the zero-feedback FET input under a different name, or a fairly simple (but potted) opamp circuit? Unknown.
As for sound, my PSAudio drives my panels with ease. Very good dynamics and high overall loudness at the same time. Image/ space is severely impacted by speaker setup in my space. The (formerly) Big Box TV between the speakers made setup even more compromised and difficult....This is NOT the fault of the amp, which has alway performed to the limit of my setup...IMO.
Other than the fact that the maximum power output is severly time limited (see B&O datasheet) this amp delivers.
For HIGH DB listeners, I'd go with a pair of of the lower powered amps rather than the Kilowatt model. Doing a biamp with a pair of the 500 watt (4ohm) will both result in more extended highs at low impedance and longer hi power time limit.