New Nuwave owner here. I'm currently using the Nuwave with a Resonessence Concero as a USB converter to the coax input of the Nuwave. I'm quite liking the combo so far. It's a reasonable upgrade over just the Concero as a DAC. Also did some comparisons of the Concero and Nuwave as USB DACs on their own.
As DACs on their I would slightly recommend the Concero to most users over the Nuwave, though some may still prefer the Nuwave depending on their taste. Both on their own are pretty decent for the money and in the same league I feel. The Nuwave generally has the edge on dynamics and detail on it's own via USB input.
The Nuwave has the tendency to sound a bit flatter in the soundstage and a more sterile or boring compared to the Concero. The Nuwave does however, have a very "fast" sound in that it seems to quickly respond and track small, quick dynamic changes (Transient response, I think?)
The Nuwave also has a noticeably blacker background, likely due to the dedicated power supply. However, the Concero seems just slightly more dynamically restrained, likely due to the lack of a dedicated output stage and power supply. There is just less "Jump" factor with the Concero. The Concero is smoother in the treble region and likely to match with a wider variety of systems.
However, when feeding the Nuwave using the Concero, the Nuwave actually seems to take on a majority of the positive traits of the Concero, while still keeping the Nuwave's excellent dynamics, speed, and black background. Immediately noticeable when adding the Concero is a much better depth of image in the soundstage
It's actually quite an addictive combo for me. Currently using the Resonessence linear phase apodizing filter feeding the Nuwave in native mode. I like to think of it as my poor man's Invicta/PWD hybrid
Of course, the Nuwave is just a beautifully built unit as well. I just wish they would make an updated GCHA in a Nuwave Chassis with some modern updates. That would be one good looking stack. Looks kind of silly stacked on my SA-31 at the moment.