Anedio D2 should be on your list. Somewhat similar to the Calyx (XMOS based asynchronous USB with Thesycon driver, ESS 9018 DAC) but no need for an external LPS to get the best performance out of it, and it has a volume control. Prime challenger for the NAD.
I don't see any reason not to get asynchronous. I've heard the argument that adaptive and asynchronous are just two peas in the same pod and sorry, but I don't buy it. There's absolutely no reason why the computer should be in charge of the timing, even asynchronous with clock synthesis is better than that. Not all asynchronous is created equal either (see Hiface at the bottom vs. Off-Ramp at the top). Everything I've ever heard about the W4S says it's implementation isn't that good. XMOS is the hot commodity right now. The Anedio uses an odd implementation, basically it's their U2 converter mounted inside the DAC and hard wired to the digital receiver with S/Pdif. I don't see any reason why that shouldn't work though, and it achieves galvanic isolation which is important when a laptop is the source.