Read both reviews (W4S and Tranquility). Not clear about how the W4S was connected to the Squeezebox and compared to the Tranquility. According to the review, they were compared in tandem, using identical Squeezeboxen. The Tranquility was connected via USB using John Swenson's Touch hack. However, the W4S being async USB cannot connect to the Touch via USB as far as I know.... if it can I'd be VERY interested in learning how.
So I assume the W4S was compared via SPDIF to the Tranquility via USB, and not USB to USB, correct?