Closer Examination

The cable is where things are also different from the HD 650, once again in a positive way. Sennheiser cables for the HD 5/6xx series tend to be quite long, with the stock cable for the HD 650 10 feet long. It is quite handy in a professional environment, where you may be going around different instruments and mixing or mastering music while you have headphones on the whole time, but the average end user will be left with a thin snake to manage. The HD 6XX goes with a 6-foot long cable of a matching black construction. There isn't much information shared about the conductor inside, but it is presumably some form of high-purity copper. With a measured impedance under 2 Ω from end to end, it's not going to be a bottleneck by any means.

The connector going to the source is the second change with the cable, with Drop switching from the 1/4" (6.35 mm) hardwired connector and an included cable adapter to 3.5 mm on the stock HD 650 cable to a native 1/8" (3.5 mm) connector. It does result in more native support, although the 3.5 mm jack was present on most mobile devices still when the HD 6XX launched. There is much to be said about using these with a phone, but let's talk more about that later. Regardless, you have the option to directly pair this with a laptop or motherboard, and Drop throws in a gold-plated 3.5 mm to 1/4" adapter for use with more prosumer/professional sources. The insulation feels quite basic, but functional enough not to twist around itself, and it stays in place in use. After a splitter closer to the other end are two wires heading to the left and right channels. This is where the connectors from before make their comeback, and these might as well be proprietary 2-pin connectors since I am not aware of any other product using them. There are aftermarket connectors for DIY applications, which does negate the pain somewhat. The connector housings are plastic and marked L/R as seen above.


Holding the HD 6XX in my hands instantly triggered nostalgia. It is so obviously an HD 650, and moving to Romania for manufacturing hasn't changed the identity and design language of these headphones. The ID is also different enough from the less expensive HD 5xx sets, with the characteristic spiral design of the plastic ear cups replaced by a more standard frame and ear cup design. Let's go through all the components in more detail, but I need to first mention the color scheme. The Sennheiser HD 650 adopts a glossy gunmetal gray color to the plastic components, which Drop replaces with what it calls "midnight blue." This is basically code for very dark blue, which looks black from a distance until light hits it at an angle and you notice the shades of blue.

This makes the Sennheiser logo on the headband harder to discern, and it is also here that we notice the headband has a more matte finish. While it's not the best looker, these are all very sensible changes that I am in agreement with. The underside gets plush foam support, split in two rather than a continuous long piece for support of the headphones on your head, without them being uncomfortable. These foam pieces are relatively firm, but there is enough give to where these should wear in over time without losing shape rather than getting loose or clumpy. The fabric cover heads into the inside of the headband on either side for a stealthy tuck without taking stitches as with a leather cover. The plastic yoke housing is where the midnight blue color is more obvious, and this is also where we see the older Massdrop logo screen printed in white and on the inside of the right ear cup, with the serial number and certification stickers on the left side.


The outside of the yoke housings are where more things change, and I knew at this point it would be an exercise in a cleaner, darker colorway. Gone are the silver nameplates in favor of black, with white-silver text for contrast where we see the HD 6XX branding on both sides. There is another, more subtle change from the HD 650 with L/R markings present to indicate the ear cups and channels, and the three dots that identify the left channel for visually impaired users got moved from the side to the front. This is a change I imagine very few will notice. While few would have been aware of these dots to begin with, I appreciate it nonetheless. Sizing adjustment comes in the form of a steel band on either side, with ratcheting points for multiple discrete steps and the entire range shown in the images above. The steel band is given a smooth black finish too, which keeps things consistent.


The other degrees of freedom when it comes to fit customization are not as allowing, however. There is slight play (~20°) in either direction, up/down or left/right. It's not going to turn 90° for compact packing, or all the way around to fold the ear cups. It is just enough flexibility to fit the HD 6XX onto human ears on a human head, no more, no less. As with most of the headphone exterior, the supports are plastic, which keeps things lightweight, and these don't feel cheap if you were worried about that.


Sennheiser is using oval ear cups and pads shaped to follow human ears more naturally, and the backs of the ear cups follow with a metal mesh design that leaves no doubts as to the open-back nature of these headphones. Tiny hexagonal holes are stamped into the grill, which allows a look at the back of the drivers inside. The stock pads are still the excellent velour Sennheiser has used to good effect on its headphones in this series, and they fit in place well with no visible gap on the side. Velour is a safe default choice. Note that pads have a significant effect on the eventual sound signature of headphones. This includes fresh vs. worn pads, let alone different pad compositions. Drop, with third-party companies, including Dekoni, sells replacement pads in different materials, such as sheepskin and hybrids of velour and sheepskin, but the recommendation is to purchase replacement OEM pads from Sennheiser to keep the original sound signature when the initial set wears out or gets too dirty. There is a thin foam sheet on the inside of the pad for some comfort if your ears are too deep and touch the inside of the ear cup, and it's accounted for in the final tuning of the headphones.


Speaking of removing the ear pads, I did as much after testing was finished for a closer look at the connecting system and drivers. The foam piece is separate and just a simple, thin foam sheet. The pads are also held in place using retaining clips on the ear cups and a plastic ring that goes all around the periphery of the pads themselves. Simply push the pads inward to loosen and remove them, and do the reverse for the installation—much simpler than the typical manner of headphone pads going through a small groove all around the ear cups. At this point, there's not much else to see unless you want to take apart the rest to get a closer look at the dynamic driver setup. It's not trivial, and I refrained from doing so. The rest of the photos above are just some cool shots I took while I was here.


At this point, only the cable connectors are left for examination, which we already spoke about. The provided 2-pin connector cable fits in such that the L/R markings end up on the outside, but one thing I did not like is that there are grooves inside the female connectors on the headphones that do not correspond to cutouts in the connector housings on the cable. You essentially force these in and carve out the groove in the housing with physical pressure, which is certainly out of character for the rest of the design. In fact, pretty much everything is user replaceable, and OEM parts are readily available. So going with this weirdly cheap implementation adds a bitter note to an otherwise pretty good hands-on experience. Once the cable connectors are in, decide upon your source and go ahead with the provided 3.5 mm or 1/4" single-ended connectors. If you feel aftermarket cables are more apt, might I suggest looking at XLR or 4.4 mm balanced connectors to a compatible source instead?