Well the PWD2 landed, the review notes are written and the Metrum will be hitting the F/S soon. This follows my journey from the W4S DAC-2 to Metrum Octave w/ AP2 to PWD2.
It's been an interesting trip. It's my first official SPDIF transport rolling experience which was its own ride. Anyone curious as to whether a digital transport can make a difference? Yes, yes it can. The level of change, key word change not improvement, from one to another is rather surprising. The onboard optical out was shouty, the EMU mixed rounded down low getting sharper as you climb, the AP2 consistent top to bottom more focused than the previous but still smooth. The PWD2 NativeX on the other hand is even further up the focus chain, perhaps too far for some which explains the love for the 2.02 firmware.
Now you can't put the PWD digital board into the Octave so... AP2 it is ;)
Getting the easy out of the way. The W4S only bests the Octave in one area... connectivity and features. It's also darker overall but shouty which makes for an odd unnatural combination when compared to others. Compared to the Octave, it also less specific in imaging, fuzzy and rolled up top even with the AP2. Long story short, look elsewhere even if you want a dark source.
The Octave in comparison, with the AP2, is more naturally balanced if still a little shifted tonally down. It's imaging is more specific but still rounded, less full than the W4S but still meaty, improved clarity and separation, very dynamic without being shouty. Essentially better than the W4S in every way while still being cut from the same cloth. Given it costs the same with the AP2, its a no brainer.
Unfortunately against the PWD2, it just doesn't compete. Given the price difference is anyone surprised? Short of it is the PWD2 is world class. I have the 2.2.0 firmware and the resulting sound is extremely focused, imaging is ridiculously specific and separation, resolution and clarity are the best I've ever heard. Tonally balanced and dynamic but not approaching shouty or overdone. Warm without crossing into overly full. Its a blink blink moment that's hard to believe :D