Audio Zenith PMx2 (Latest Iteration, Mid-2017) - Impressions and Measurements

Alex sent me the latest iteration of his PMx2 prior to kicking off the ongoing tour. On top of being busy, I wanted to see what the first few listeners would say about them prior to me posting anything. Beyond that, I don't think these need much of an introduction.

The most visible change with the latest iteration is the use of leather pads and some cosmetic tweaks, such as silver painted grills. I'm sure Alex has done other work inside the headphones as well.

First, a bit of my personal background and experience with the PMx2. Some of the earlier PMx2s, I believe non-production, were tuned not too unlike the HD650, but with more sub-bass. Alex eventually moved to a more neutral-across-the-board tuning. I've measured several iterations as he's worked on them. The later, more neutral models were just that, very neutral, and with improved technicalities and distortion over earlier iterations. However, I felt the headphone sounded a bit restricted in the low-end. They sounded a bit overdamped. Most planars don't have the same sense of slam and impact to me as a good dynamic despite their extension if tuned very neutrally. Still, the PMx2 that people have experienced for the longest time have had a reference tone to go by for the most part.

Moving forward to the latest iteration, here are some general impressions:

- Bass more closely matches some earlier iterations I heard, in that the low-end does have a slight emphasis. Think HD650, but instead of dropping off after the mid-bass hump, it just keeps going into the lowest registers. (But, still, I think this is necessarily to give planars a sense of slam and power, so it's not entirely equivalent.)

- Midrange and treble are just about as balanced as previous iterations.

- I've always measured the PMx2 as having a bit of an upper-mid depression. I never really heard it before, because earlier pairs had more neutral bass. With the stronger bass this time around, this depression sticks out to me. For a lot of music, it's no problem. It makes them sound slightly relaxed. For rock and some other material, that area is critical for generating a key part of the music's sharpness and presence. With some material, the latest PMx2 can sound a bit muted and wooly because of this. But, again, most music will not at all be affected.

- This upper-mid depression coupled with the extra bass also makes the treble stand out a bit more than before. It's not that the mids and treble have really changed much, but with the bass taking on more of a role, the relative nature of things has shifted around. On some amps, this may cause the PMx2 to sound a bit raspy and edgy. On some other amps, it's a complete non-issue.

- The sense of air and staging is different with the new pads. I think velour is prone to sounding more expansive and airy than leather. Still, I've never found any planar to really match the stage and air of a really open sounding dynamic headphone, and the PMx2 has never been an exception to me. But, for what it is, air and stage are pretty good on the PMx2. This is not a huge concern to me. It doesn't have a really flat stage, it isn't too hard left/right, nor is it too 3-blob-like. It's a fine, balanced, but not attention-grabbing approach.

- The latest PMx2 probably sounds the least damped, i.e. not overdamped, and restricted of any iteration I've heard. It sounds more alive, sharper. This is a good thing.

- Bass quality is excellent overall. Good tone, good extension, and low distortion. On the right amp, it's clear that it can best many dynamics.

- Very clear and fast sounding. Though the upper-mid depression can get a sense of a lack of sharpness and detail, if you listen past that, the PMx2 rarely trips over itself. Very controlled.

- Circling back to some comments on tone, mostly focused on the extra bass and upper-mid depression, I still want to be very clear this headphone has a more natural, reference tone than almost every other headphone on the market. I think the HD650 is better balanced in the mids and treble, but the PMx2 does best it with bass. They are more close overall than not.

- The right amp makes a big difference with the PMx2! It's not so much that they scale like the HD650, but you definitely need to be concerned about amp and headphone synergy. The PMx2 can sound decent from certain phones and DAPs. I did not care for how it sounded with the Pono player.

Overall, the latest PMx2 continues the trend of having about as much of a reference-quality tone as you can find in the headphone market. It's not slouch with technicalities either, nor will it ever offend or slap you upside the head in an attempt to show off. I still think some of the best dynamics with uber rigs can have more technical prowess, as well as being more my preference anyway, but the PMx2 has its own upsides. It's certainly one of the best, most well-rounded headphones out there. For that, I can nitpick, but I have a hard time really faulting it.

 

Frequency response shows a balanced but somewhat bassy/warm tilt. In actual listening, this boosted low end helps counterbalance what I hear as an inherent "wimpy" sounding nature to most planar drivers. This actually closely matches the HD650.

You can see the 1-5KHz area in general is a bit depressed. Not horribly so, and gently, but it can affect certain genres of music. Similarly, the spot around 6-7KHz can relatively stand out compared to the upper-mids, so certain amps can make this stand out. The absolute levels are totally fine, but listening isn't always cut and dry like that.



CSDs are very clean. Not much else I can say. (I feel like a lot of planars I've heard lately have really dirty CSDs. What happened to all the ultra-fast, ultra-clean planars?)



I would hope you are all familiar with the distortion limitations of my rig by now. The PMx2 is pretty close to being about as good as it gets on my rig. Low distortion across the board. Alex did a fantastic job driving down the PM-2 driver's midrange distortion!



Comparison FR graph against my modded HD650. On the PMx2, you can see the bass keeps going, the upper-mids are 1-2dB lower in comparison (HD650 is perfect for me there), and the 6-7KHz spot is just a hair more evident. Much more similar overall than not. These are my two favorite headphones in terms of tonal balance. And the PMx2 sounds great with a bit more weight on the low end!

 

I actually heard the Pono as thin, papery, and rough sounding with the PMx2.

 

The tour unit is the one I measured. First thing I mentioned. And why wouldn't I listen balanced if provided the cable to do So?

For me it was the lack of bass and the lower treble sounded quite off. Digital sounding. Could he the sabre DAC, even despite the digital filter they use.

 

I mean, you might be able to match it in terms of response, but the HD650 is always going to sound a bit less clear than the PMx2 in the bass department. I think with enough Dynamat and other mods, folks exaggerate the difference. Not to mention I think the HD650 fed with a good OPT-coupled tube amp will sound, well, more dynamic and slamming than almost any planar (even a planar with elevated and clean bass). I know there will be exceptions. The OPPO driver to me always sounds a bit restrained in that sense at least.

Still, you can't EQ out distortion.

As for PMx2 vs Utopia:

 

Here you go guys. Both from the LA meet 2017

 

Comparo with the analytic hell of the HD800



Relatively speaking, much more treble and upper tilt than the Utopia. I do hear the HD800 like that relative to Alex Oppos and the Utopia. Without regard to price, I would probably pick Alex Oppos and the Utopias over the HD800s.

HD800 are IMO analytic, and relatively speaking that's indeed what the plots kind of show.