My apologies if I have come across as "harsh", as that was surely not my intention. I was simply trying to address the facts as they pertain to this amp design.
I agree that there is much more to sound quality than the feedback design, but on the other hand, with these class d amps, the final results are in fact greatly dependent on this particular part of their design. In fact, several class d designers have said that the final sound of a class d amp is heavily dependent on the both the type of output filter (air core is best) and its implementation. It is THE critical component. Have you tried replacing the ferrite core inductors with air core? You may be very pleased with the results....
There is no escaping the fact that distortion with frequency and power output climbs significantly, as does output impedance. One does not see this at these levels in the designs which keep the filter in the loop. It is also a fact that the output filter must be designed to a point load impedance, and this is less than optimal when using a load which is variable. This is all simple science. Is it audible or not? Well, there have indeed been people less than satisfied with the HF response of other amps of similar design, so for some it is clearly an issue. Will it be an issue with this amp? Time will tell.
Since the manufacturer is generously providing a 30 day trial period, the potential users are free to decide for themselves whether or not the above behavior is audibly significant for themselves. I light of the positive reviews many similar class d amps have gained, I am sure this amp will too be enjoyed by many.
Best of luck to Kevin...