CanJam at RMAF 2014 Showstopper: Sony's Proposed New Industry Standard for Headphone Plugs!

I knew going in that Sony's booth would be an RMAF highlight for me. Their new MDR-Z7 headphone with optional cables by Kimber Kables (here, here, and here) driven by the PHA-3 portable balanced headphone amp/DAC were a must hear. I heard, and I was very, very impressed. Samples for review consideration are winging their way towards Montana as I type.

But, as good as that was, there was something else in the Sony booth that absolutely blew me away!

About 15 years ago, as CEO of HeadRoom, I decided that because some high-end power amps for speakers were balanced designs, and because headphones are like miniature speakers, what the world needed was a balanced headphone amplifier. Not long after, HeadRoom introduced the BlockHead, the world's first balanced headphone amplifier.


The BlockHead was not only a balanced design, it was also a true mono-block design where left and right channels were completely separate. It's a bit hard to see in the picture above, but it had two chassis that were held together with a common front and rear panel. It also had two power cords, two volume controls, and, by necessity, two 3-pin XLR connectors for the left and right channels going to the headphones. (Pic of BlockHead internals.) I had no idea I was creating a standard for balanced headphones plugs...hell, on some level it was just a marketing gimmick to gain audiophile attention for headphone amps. (Though I do believe the loss of the common ground, effective doubling of slew rate, and slight reduction in harmonic distortion do make it a superior, though more costly, way to drive headphones.) And it did indeed get attention, here's Jonathan Scull's Stereophile review of the BlockHead.

Well, once balanced headphone amps became a little more common and made in a single chassis, the need for two XLRs disappeared and a single 4-pin XLR started to appear. Then, when Ray Samuels decided to come out with a balanced portable that wouldn't have room for an XLR connector, he introduced what we call an RSA connector as a jack for balanced portable amps. Unfortunately, the RSA connector is a bit too big for portable media player use, so when HiFiMAN and Astell & Kern produced balanced portable players they used 2.5mm TRRS jacks...but they're wired differently! Aaaaaaaargh! We have too many balanced headphone connectors! What we need is one single standard, damit.

Enter Sony and Naotaka Tsunoda's brilliant idea for a new headphone connection standard.


Between the standard 3.5mm and 6.5mm headphone plugs is Sony's new proposed standard, a 4.4mm TRRRS connector that can be used for both balanced and unbalanced headphone connections.

Naotaka believes the world needs a new headphone connection standard and is proposing a 4.4mm TRRRS plug and jack as the solution. I didn't quite catch up to the awesomeness of this idea until I reflected on it subsequently, but this new connector could have some really great benefits, it seems to me.

  • Though phones and slim pocketable devices would continue to need the 3.5mm standard (or something smaller—think Lightning jack), all other headphone jacks portable or stationary, could use the new connector.
  • Both balanced and unbalanced headphones could be compatible with both balanced and unbalanced headphone amplifiers. If wired properly, anything could plug into anything!
  • The headphone jack is quite low-profile and would work well in high-end portable applications.
  • Built well, this jack on a portable would be fair less prone to mechanical failure from being yanked around.
  • Built-in cable or accessory 3.5mm-to-4.4mm adapters could be very small.
  • Designed well, contact resistance for this connector could be quite low.

I think this is a grrrrrreat idea! And Sony is exactly the kind of company that can pull it off. My fingers are crossed.

But that's not why it was the show stopper for me...

When I can draw a direct line between something I did 15 years ago and something Sony is setting out to do today, well, it's both personally satisfying...and weird. I guess I mostly feel grateful to be a part of the headphone world and happy to see the echo of something I did in the past show up so clearly. Cool beans. Go Sony, go!


Chrisknos's picture

The Sony XBA-Z5 iem? It has roughly the same pricing as the Z7.

Za Warudo's picture

Which one did you like more, the Z7 or the PM-3 prototype. I know it's too early to make any judgements on the PM-3 and the Z7, just want an rough impression. Which one sounded more neutral?

Tyll Hertsens's picture's way too early to make a comparison.
RPGWiZaRD's picture

Those would be very interesting ones to me, they are improved R1 versions and deserve some attention.

mir's picture

Hi Tyll,

do you plan on reviewing Sony MDR-7520 sometime?


Impulse's picture

You really think Sony has the clout AND smarts to successfully promote a new standard tho? A lot of people still associate Sony with anti-standard proprietary stuff like memory sticks, MD, etc. I think they're the TYPE of company that can develop and pursue this, certainly, just not sure their execution will be successful.

It reminds me a bit of their camera division which has brought a ton of innovation lately that has shaken up the camera world (1" sensor compacts, better mirrorless AF tracking, first full frame mirrorless, etc), but their execution is still shaky and they seem to move from one thing to another too quickly.

I do wish them the best, I don't think i own anything Sony right now but I'm keeping my eye on their Z3 phones... Seems like they're closer than they've been in years to rising to a position of leadership in several different consumer markets. If they could just tie it a all together...

Dopaminer's picture

IMO better than all the above single-plug options is the hirose connection used by iBasso and Mr.Speaker and some iem/amp combos. Short, strong, secure; why on earth do we need yet another format, especially one as long as the Sony?

Tyll Hertsens's picture
Well, it's important to remember we're talking about a new standard for all headphones (or at least, all headphones intended for audio reproduction only---smart headphones will need a digital connection). As such, it needs to be VERY cheap. The Hirose will never be as inexpensive as the Sony proposed plug, and labor to assemble is substantially different. Also, any manufacturer who is currently making TRS-style plugs and jack will be able to tool up for the new connector with relative ease.

The new connector does have a couple of problems. We'll still have to live with a connector that can short out the contacts when being inserted (but we're already doing that anyway), and I would guess that cross-talk is tougher to control relative to multi-pin connectors. But high-end headphone companies can always just use any connector they want. Again, this is for the broad consuming public and if it does get introduced, consumers will notice the change and possibly become curious about balanced drive and become a little more aware of headphone performance. Maybe...

DisCHORD's picture

All they'd need is to get some companies to jump on with them, and start using the new connector. Maybe Sennheiser, Apple (though I doubt Apple would care enough to do it.), FiiO, and some other big companies can put this on their new products.

TheAudioGuild's picture

I still can't bring myself to get on the whole "balanced" buzzword bandwagon, let alone get excited about a new plug standard proposal. Oh well. At least for a while this morning it was looking like it was going to be a pretty good Monday.

eugenius's picture

I would have preferred some kind of trick flat tab or pin connector like an XLR but with tabs / pins in line - not a bigger jack. And make it waterproof and thinner than a 3.5mm but with more secure contact points.

zobel's picture

Here is a pretty good, simple overview of the differences between balanced and unbalanced design;