The sonic goal of the NW-WM1Z was quite simple: To compete sonically with the best non-portable, room-based digital playback systems currently available. In my opinion it succeeds at this goal, with a few caveats. Unlike some portable players that are unable to create the same big soundstage and sense of unlimited bass capabilities as desktop or room-based components, the NW-WM1Z rivals any AC-tethered headphone playback systems I’ve encountered when it comes to producing a full-sized image with subtle and fully realized sonic information.
The terms “smooth” and “suave” featured prominently in my listening notes on the NW-WM1Z. Regardless of the source material’s format, this player always sounded in complete control. I attribute this overall sense of natural ease to the NW-WM1Z noise levels, which are lower than those of most portable players (and many room-anchored components). On material that I know well I noticed the lack of anything that could be labeled as “distracting base-level noise.” It was not only easy to listen deep into the mix, but there was an overall sense of musicality and lack of artificiality or hi-fi-ish edge. How “natural” does the NW-WM1Z sound? I preferred the overall sound of the NW-WM1Z playing back my own recordings to those same recordings played back directly from the Korg MR-1000 they were originally made on. Through the Sony NW-WM1Z these recordings sounded less mechanical, more fluid, and more natural, similar to the original microphone feed.
With its 10-band EQ you can alter the NW-WM1Z’s sonic character rather drastically, if you wish. Most of my serious listening was done with the “direct” mode engaged, which bypasses all sound-shaping. I also listened to all the various DC phase linearizer settings and found that their main function was to change low bass character, and the “best” setting was directly related to each individual track rather than to a universal ideal. Also, your choice of headphones will have a profound effect on the amount of change the DC phase linearizer setting will make. Unless your cans can produce deep bass you may not hear much difference between settings on and settings off.
My favorite pairing with the NW-WM1Z was the MDR-Z1R headphone using the balanced connection. This combination provided a silent background, a huge but exceedingly specific image and soundstage, super-deep bass response, a musical yet detailed midrange, more than enough gain for even quiet source material, and an effortlessness to the dynamics that gave everything an easy-to-listen-into character. In-ears with anywhere between 90 and 100dB sensitivity interfaced with the NW-WM1Z’s single-ended output perfectly with no hiss and plenty of gain.
The only headphone I could access that had the necessary 4.4mm-terminated cabling as well as a single-ended cable to do a direct comparison between the NW-WM1Z’s single-ended and balanced outputs was the Sony MDR-Z1R headphone. If I can generalize from the differences I heard between the single-ended and balanced connections using these relatively easy-to-drive headphones, I would recommend getting an adapter or a new cable that supports the 4.4mm balanced output for whatever full-sized headphones you plan to mate with the NW-WM1Z. Using an amplifier capable of 4x the drive of the single-ended output made a big difference in the size and scope of the sonic presentation. With the balanced output the overall sound was fluid and effortless, and the bass was better in every way compared to the single-ended output.
If my only measure of overall value were sound quality, I would have to rate the NW-WMZ1 as the best portable player I’ve reviewed. But if you factor in portability, flexibility, and options for inputs and outputs, the NW-WMZ1 has some limitations that may well affect whether you find it to be your ideal portable player.