Design.

A Signature Series Sony WM1 DAPs were introduced in 2 flavors, WM1A and WM1Z. While overall design is similar, each one has its unique elements. With 1Z having a more premium cost-no-object design, it has 256GB of internal memory (vs 128GB offered in 1A), 1Z has more premium internal components (newly developed high polymer FT CAPs and surface mounted Fine Sound Registers), and the four-wire braided Kimber Kable connecting circuit board to headphone jack. But the biggest, and I mean the “biggest” difference is with a chassis material and its corresponding weight.

Sony starts by milling chassis from a solid block of pure oxygen free copper (OFC) material, using copper due to its higher density and lower resistance when compared to aluminum material used in 1A chassis. Then, copper material is gold plated to prevent the oxidation. As a result, the chassis of 1Z serve as an extension to the circuit board ground. Since I don’t have access to 1A, I can’t tell you exactly how these DAPs compare, especially due to a difference in selection of internal components and headphone jack wiring. Certainly, aluminum has different electrical properties, including the reduced conductivity. In theory, the ground plane serves as a return path for a power to all the devices on the board, and the higher conductivity of the return path should result in cleaner power and lower noise floor. At the same time, pure copper adds to the weight and the cost when comparing 1A vs 1Z. Thus, you have to consider a trade-off, especially when we are talking about 455g of weight.

With chassis discussion out of the way, the next thing that grabbed my attention was the all glass top display where the visible screen area is 4” with FWVGA 854×480 pixels resolution. It’s a deep color display with black and white high contrast scheme. Besides being able to display rich colors of the embedded artwork (depending on the picture size, since some of the graphics wasn’t displayed), everything else is black’n’white, with an exception of a few labels in yellow. WM1Z has a touch screen with a very responsive display, no lags what to ever in fw 1.2/2.0.

Looking around the chassis, you will find a Hold slider on the left side, to lock the touch screen functionality. On the right side, you have 6 multi-sized hw buttons, with smaller Power button all the way at the top and charging pinhole LED next to it, two larger Volume +/- buttons below it with a distinct bump on the + button for a blind id, and below it 3 transport control buttons with larger Play/Pause in the middle and smaller skip/forward on either side. Play/Pause button also has a bump for a blind id, just slide your finger without looking at the controls and you will be able to easily feel Volume Up and Play/Pause buttons.

These buttons itself are all metal and gold plated, very durable, no shaking or rattling, with a tactile feedback when pressed, and overall solid feel like they are part of the chassis, stamped right into the gold-plated copper. The ergonomics of the design is very impressive. Due to the weight distribution of the 1Z, my thumb was comfortable controlling the Power (for screen on/off) and adjusting the Volume. For transport control buttons toward the bottom of the right side, I had to slide my right hand down and use both hands, with left one for support to make sure I don’t drop the DAP.

Lower left corner of the 1Z bottom has an opening to loop wrist strap, and also a little notch for securing Sony’s leather case. In the middle, you have 22-pin WM port which is proprietary to Sony, and used for charging the DAP, connecting to computer to transfer the files, and also for digital out. No analog Line Out is available, only the digital transport output to drive external DAC/amp. Next to it, in the right corner at the bottom, is the dust cover for uSD port which can accommodate 256GB card and probably the latest 400GB as well. Next to it, you will also find another notch for Sony’s leather case to latch to. The back of 1Z has a leather-textured rubbery non-slip material with NFC marker when pairing wireless headphones, if NFC is enabled.

The top of 1Z has 3.5mm TRRS single ended stereo headphone jack on the right, rated at 60mW+60mW (at 16 ohms), while on the left you have 4.4mm TRRRS balanced stereo jack, rated at 250mW+250mW (at 16 ohms). 4.4mm is a new JEITA standard designed specifically for balanced headphone jacks. It has a number of advantages, such as being mechanically stronger and having a reduced resistance due to larger cross-sectional area of contact. WM1 uses a brand name Nippon DICS Pentaconn (named after 5 contacts) jack where each connection (L+/L-/R+/R-) has 2 points of contact, made into C shape with both sides of the plug engaged, leading to a larger area of contact which results in lower resistance. For additional failsafe, balanced port has a relay switch, making sure you connect headphones all the way in.

Under the hood.

In my DAP reviews, the “under the hood” section usually starts with a discussion about which DAC is used in the design. And often the discussion continuous talking about using dual DACs in higher end models to separate L/R channels. WM1Z is different because Sony has a totally different approach to this design requirement – using their own digital S-Master HX amplifier.

S-Master digital amp is not a brand-new concept, Sony has been using it in a lot of their high-end desktop audio systems throughout years. But they continue to perfect it, to optimize it, and to adapt it for a portable use with their latest in-house developed S-Master HX semiconductor digital amplifier – model CXD-3778GF. This new evolution of S-Master HX digital amp wasn’t only optimized for efficient battery use, but also developed to be compatible with native DSD decoding, Balanced output, and High-Power output. Keep it mind, other entry and mid-fi Sony DAPs, like A40 and NX300, also use CXD-3778GF model, but they have a different implementation of LPF circuit where, for example, A40 uses switching FET inside of CXD-3778GF, while WM1 has high voltage FET outside of the digital amp.

I already mentioned “digital amp” a few times, and would like to talk more about its benefits. In a traditional design, decoded digital data stream is fed into D/A converter for digital signal to be converted into analog, then some Low Pass Filter (LPF), perhaps a volume control, and analog headphone amplifier section. Such traditional design generates “open-loop” distortion which is corrected with a Negative Feedback that has its own problems. Also, with a traditional off-the-shelf DAC architecture design, we see more dual DAC implementations to separate L/R channels in order to reduce the interference and crosstalk.

The problem with this architecture is that majority of the signal goes through analog path which is more susceptible to noise coupling, interference, and crosstalk. Even with L/R channel separation, you are still dealing with a small printed wiring board (pwb) and close proximity of the signals. What S-Master digital amp does is to completely replace the analog amplification with a digital amp technology without a feedback. S-Master doesn’t have D/A converter. Instead, the amp processes the digital signal until the final output stage where it uses LPF.

In a digital domain, there is no need for a dual DAC since you don’t have to worry about analog signal interference and crosstalk, and because this is a fully custom semiconductor design, Sony is in full control to optimize the audio performance (in this case supporting balanced output with DSD native playback in balanced mode only of up to 11.2MHz and Linear PCM playback up to 384kHz/32bit), and also to optimize battery life depending on the audio format playback. When it comes to audio formats, you have support of most of the lossy and lossless formats, such as MP3, WMA, FLAC, Linear PCM (wav), AAC, HE-AAC, Apple Lossless, AIFF, and DSD. CUE files playback is read as a single file. Also, although there is no menu selection to enable gapless, I tested it with one of my gapless MP3 albums and it worked flawless.

Battery life is truly phenomenal, Sony was able to optimize the performance, depending on the file format, to have a playback of over 30hrs. I ran multiple tests with MP3 and FLAC files, using balanced output, and with direct sound on (no DSP effects) and off. On average, my best-case scenario of playing 320kbps MP3 from 4.4mm HO with direct sound yielded 32 hours of continuous playback. Switching to FLAC, playing continuously from 4.4mm HO with DSP effects enabled – lasted 19 hours.

Page 3: GUI and DSP Effects.

Page 4: Sound analysis, Comparison.

Page 5: Pair up, Wireless connection, Conclusion.