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Impressions: ddHiFi DJ44S for Sony Walkman WM1Z


To ground or not to ground – that is the question. Unless you’re an audio engineer or serious enthusiast, you may not understand the ins-and-outs of electrical signal grounding, especially when it comes to digital audio players and balanced cables. Count me among the group of those for whom grounding meant very little, until recently…

As a long-time user of Sony’s venerable Walkman WM1Z, I’ve often wondered about the occasional debate that flares up in audio communities about the grounding (or lack thereof) of the 1Z’s 4.4mm balanced headphone output. 

It turns out that Sony engineers decided to use a non-conventional method of signal grounding with both the Walkman 1Z and 1A: via a ground pin in the 3.5mm output port to the chassis. That means that a 4.4mm balanced cable that lacks a dedicated fifth or grounding pin won’t get the inherent sonic advantages of the 1Z’s chassis grounding. 

It actually gets more complicated than that, as I’ll explain shortly, but for all intents and purposes, let’s assume the 1Z is generally not grounded with a large number of standard 4.4mm cables.  

That’s where the subject of this review, ddHiFi’s DJ44S 4.4mm ground pin adapter, comes in. It essentially couples the 4.4mm output with a ground pin that’s inserted into the grounded 3.5mm output port, and therefore passes on the grounding advantage to any 4.4mm cable that’s used with the adapter in place. 

Why is this important? Let’s find out. 

Keeping grounded

Grounding is far more common in the desktop world, where devices connected to AC mains power need a dedicated electrical pathway to reject noise and interference from the grid and other electrical equipment. 

In a nutshell, grounding creates a reference point (zero volts) for the voltage of the audio signal inside a digital audio player, diverting noise and other electrical interference away from the audio circuit. It’s called grounding because in the case of mains-connected electrical equipment, the grounding channel usually goes to ground – literally.

By reducing noise and interference, grounding has several sonic advantages, not least a darker background that creates a perceivably larger soundstage. A cleaner signal also helps improve resolution, and increases the impact of certain frequencies, typically bass.   

Some people argue that because digital audio players use batteries, the audio signal can’t actually be ‘grounded’ in the same way as mains-powered equipment. But they can, in several ways, actually. 

The first (and least practical) is connecting the DAP’s metal chassis to an external ground reference point, like a dedicated grounding box or a grounded piece of equipment, using a shielded cable. This can help divert noise away from the internal circuitry, but doesn’t really make sense for a device you’re carrying around with you.

Another is by using shielded cables. Cables like PW Audio’s Orpheus (reviewed here) and First Times Shielding (reviewed here) feature dedicated shielding material to minimise noise pickup from external sources. This is similar to, but not always the same as using balanced connections; simply using 4.4mm balanced connections inherently rejects common-mode noise, even without perfect grounding.

Lastly, and as introduced above, is Sony’s method: use the chassis itself as a grounding device, but this only works if the 4.4mm balanced cable you’re using has a grounding pin. Since many don’t, you’ll need to find another way to connect your cables to the Walkman’s chassis.

The DJ44S solution

ddHiFi’s DJ44S M1 is designed specifically for Sony’s original WM1Z DAP, with its integrated (but only selectively connected) chassis grounding pins. The ddHiFi adapter bridges the gap between standard balanced cables and the DAP’s grounding mechanism by inserting a grounding pin into the 3.5mm headphone output port, which is then physically connected to a 4.4mm plug inserted into the DAP’s balanced output.

The result: a fully-grounded all-new 4.4mm output port, ready and waiting for your cable of choice.

If you’ve ever seen or used a WM1Z Walkman before, you’ll know how meticulously it’s been designed and built, the sheer quality of its gold-plated solid copper chassis spawning the DAP’s ‘Gold Brick’ nickname. It stands to reason that any adapter you’d likely want to use with this marvel of industrial engineering should likewise follow the same design language and build quality.

DJ44S is not the only WM1Z ground pin adapter on the market, but as far as I know it’s the only one that preserves the Walkman’s gold aesthetic as closely as possible. 

Unlike the WM1Z, the moulded outer shell is made of a lightweight aluminium alloy, anodized in gold to match the colour of the Walkman’s 24-carat gold plating. Internally, the adapter uses a 25.5awg 6N OCC copper cable and lead-free gold solder to connect an original Pentaconn 4.4mm balanced plug to the DAP’s 4.4mm output, along with a 24-carat gold-plated ground pin that, as described above, fits into the grounded 3.5mm output port. 

The ground pin is much shorter in length than the 4.4mm plug, and for good reason: to prevent damaging the plastic 3.5mm port when inserting and removing the adapter. If the pins were the same length, the force placed on the 3.5mm port could potentially cause it to fray over time. 

Other than this rather clever design detail, everything else is as simple as it seems: plug it in, plug in a 4.4mm cable, enjoy grounded (and balanced) sound output. It even fits onto the WM1Z without having to remove the TPU case I use to protect my Walkman.

Sound impressions

Playing just a few test tracks back-to-back with and without the adapter in place makes it quite obvious that grounding does, in fact, have an audible effect on sound quality.

I tested the DJ44S with a new IEM I happened to have on hand for review, FIR Audio’s e12 (review coming soon). Out the box and using its stock cable, this IEM is quite bombastic, revealing, and – for want of a better word – edgy. Some of its tuning quirks push the sound to extremes, which makes it quite easy to hear where the grounding changes occur.

With the DJ44S in play, I hear a cleaner sound. The slight grain I picked up in the midrange and treble frequencies using the WM1Z in its ungrounded state is significantly muted with the adapter in place. This results in a less fatiguing sound, and an easier appreciation of the e12’s inherent resolution. The darker background also makes some details easier to pick out, and stage feels slightly expanded in all dimensions.

It’s important to stress that the changes I describe above are subtle, but because I’m listening with a high-quality transducer and one of the world’s best sources, they’re also easy to pick out and describe. In other words, I don’t have to strain to hear the differences.

If there’s any downside at all to this adapter, it’s that you’ll want to avoid plugging our unplugging your cable while the player is still switched on and with IEMs in your ears. Doing so sent a loud feedback loop through the cable and earphones, making me jump out my skin more than once. I guess all that residual noise has to go somewhere…

Closing thoughts

There are many different layers to achieving great portable sound. Using the best gear, like Sony’s Walkman WM1Z, is always a good start. But even then there are ways to keep pushing the envelope, and making sure your balanced cables are properly grounded is one of them. 

Since you can’t always be sure your cables are grounded – or shielded, for that matter – ddHiFi’s $100 DJ44S M1 adapter is basically a shoe-in for WM1Z users. The only reason I’d consider not buying one is if you feel it adds too much bulk to the player (preventing it from fitting inside a compact pouch, for example), or if you know for sure your cables are already shielded, in which case adding a grounding pin adapter won’t make a significant difference.

Practically-speaking, the adapter also changes the angle of entry for the 4.4mm port, which could affect how flush your IEM cables sit with the player.

But all these nitpicks are just that. The adapter is small, light and robust enough to carry with you and use only when required, and looks like a matched custom extension to Sony’s Gold Brick if you just want to leave it permanently attached. Either way, I recommend the ddHiFi DJ44S without reservation. 

You can purchase the ddHiFi DJ44S M1 from LinsoulHiFiGo and Amazon, among other reputable online resellers. 



Picture of Guy Lerner

Guy Lerner

An avid photographer and writer 'in real life', Guy's passion for music and technology created the perfect storm for his love of portable audio. When he's not playing with the latest and greatest head-fi gear, he prefers to spend time away from the hobby with his two (almost) grown kids and wife in the breathtaking city of Cape Town, and traveling around his native South Africa.


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