I received my new HD6XX a few days ago and I couldn't help but compare them to my H6 Gen 2. In all honesty, I was expecting the HD6XX to sound way better than the H6, but that really wasn't the case at all...in all honesty, to my ears and to my surprise, they don't sound too far off from one another...which is great! The signatures are different, but in terms of sound quality alone, the H6 matches up very well against the HD6XX. Now, I do think the HD6XX sounds better, but it is, after all, considered by many to be one of the greatest headphones of all time. Also, when I first put the HD6XX on and listened to them for a while, they left a greater first impression than the H6 did. It took me a bit of time to warm up to the H6. Another thing that surprised me, the HD6XX sounded great to me only off of my MacBook and got loud enough. I did order a Magni 3 and it is still on the way, so I will plan on plugging both headphones into it but I'm not expecting it to make a huge difference at this point.
To break it down more I will compare the attributes between the two, starting with the bass; The HD6XX is known to be mid-bass heavy and thick, but lacking in extension. The H6 is the opposite. It has an accentuated and deep sub-bass, but a slightly cooled off mid bass. Comparing songs with the two, I felt that I wasn't missing anything on the H6, even with the mid bass dip. While the HD6XX has a little more body in that region, the H6 doesn't feel completely empty, and the accentuated sub bass adds a little warmth to the H6, but not as much as the HD6XX. I also find the H6 bass to be tighter, and some mid-upper bass notes sound quicker and actually a little more accurate; these notes on the HD6XX hang around a little too long and create a bit of mud. I think the HD6XX bass is good for music that benefits from a little extra warmth but the bass of the H6 sounds tighter and more textured to me.
The midrange is the strongest attribute of the HD6XX and was expecting it to sound worlds better than the H6 but once again to my surprise, it didn't run circles around the H6 at all. While this one area is the only one where the winner is more clear (the HD6XX wins) the H6 still holds it own, and honestly, the midrange of the HD6XX sounds better clearly on only certain songs. The H6, to my ears, has a slightly more pronounced upper midrange and lower treble, along with the aforementioned mid-upper bass/low mid dip. This makes some vocals that already have some reverb/echo effect (Marvin Gaye's "What's Going On" was a primary example) even more pronounced, and a little thin and artificial and lacking body, and also a little bit of ringing on rare occasions. The mid-bass warmth of the HD6XX fills in this body beautifully. However, on tracks where vocals don't have this problem, both sounded pretty close to my ears. The rest of the midrange sounds pretty close to my ears, horns, guitars, sounded only slightly better on the HD6XX during my initial comparisons, where it has a little more texture and resolve over all. The H6 handles them just fine. The only other (small!) problem area I can think of, which was kind odd, was some deep synthesizer tones sounded more natural on the HD6XX too; they had more midrange tonality, the H6 sub bass made it sound a little "bassier" than it should. I think. To summarize, the H6 midrange does sound a little thin and a little hollow, but compared to the HD6XX, not as much as I had initially assumed.
The HD6XX treble is famously relaxed slightly. This is the one area where the H6 is a little more accurate as the HD6XX clearly misses some treble sparkle and also lacks air, leaving the sound thick and dark, nice for relaxing, but the quickness and airiness of the H6 treble is missed a bit. Once again, because of this it allows the HD6XX midrange to sound a bit more pronounced and warm, but it's harder to hear the details on the HD6XX. Also, because of the airier treble of the H6, it has a better soundstage to my ears, with more width and height, while the HD6XX has a little more intimacy. Sometimes it's good to have air and space, other times it's good to have intimacy. Instrument separation is about the same on both headphones to my ears.
I have to say, now having a great headphone like the HD6XX to compare the H6 to, I can say that the H6 holds up much better than I thought. One thing I will say, to be honest, I feel just a little bit closer to the music with the HD6XX, and I think it's due to the warmth and the tone of the midrange, and the intimacy of the soundstage. The H6 is more extended but also maybe a little more analytical. One of the H6's biggest criticisms I've read about was it's timbre, and yeah it's not quite as good as the HD6XX but it's pretty close to my ears. It's not bad at all.
I'm happy to own both of these headphones. Because I do like the HD6XX a little more, it will get quite a bit of use, but I can't use them at work or on the go, and that's where the H6 comes in, and I can still expect a solid performance from them.
I don't think the H6 gets the recognition it deserves.
