The Amazing Super Duper Underrated HD650.
A Headphone That Kicks Serious Ass And Should Be Considered Before Any Other Thousand For Multi-Thousand Dollar Purchase.

I cannot emphasize how good this headphone is, even for those with a lot more money to spend. Sennheiser veil? Dunno anything about that. This is 2015. I purchased these HD650s from Amazon a few weeks ago. We aren't in 2007 anymore.

I decided to pick up the HD650 because I wanted something a bit different than the HD600s. More of a return to the slightly dark sound that I've always preferred. By slightly dark, I do mean slightly dark. A gentle downward slope. Not rolled off to shit. Also, if there was one thing that bothered me about the HD600, it was its slight vocal harshness, a bit shouty at times. This characteristic of the HD600 didn't do any favors with the mastering of the second and third Taylor Swift CDs. The idea of my actually buying the HD650 originated from my working at EC. Craig doesn't have any super headphones (I was too lazy to bring my own into the workshop for two weeks), so the best stuff on hand were the HD600 and LCD2r2 (special cherry-picked edition). I found myself using the HD600s the most often to assess sound quality. So I ended up purchasing the HD650 variant for the reasons mentioned above.

I don't exactly know what the differences are between the HD600 and HD650 drivers outside of a slightly different FR, but it does seem like that the HD650 driver is better damped, more controlled, more refined. The HD600 driver sounds looser - less controlled. What was surprising to me that some of the older HD650s had a depression the upper mids and similar bass, but this one wasn't like that all at. This HD650 had a very similar FR response as the HD600 outside of a slight bass elevation around 100Hz. Maybe this is why people who heard this particular HD650 didn't think it sounded veiled at all.

This latest HD650 has semi-transparent driver that you can see through. There is a semi-permeable baffle (see third picture down) extremely similar to the HD800 metal mesh material. I assume this baffle material does quite a bit to maintain low bass extension. The Sennheiser engineers are pretty amazing. I did few tweaks (not invented by me, but can be seen all over the Internet) to liven up the HD650s sound. The tweaks don't change the measurements that much. The measurements pictured are with these tweaks in place:

• Removal of the foam behind the driver. Pop the cage cover out. Push in the foam with tweezers (see red arrows). Then pull the foam out from the middle. This mod should be reversible if you are careful.
• Quarter mod. Put a quarter in the middle of the foam covering the driver on the insider. Cut around it to make a hole. I tried not using the foam at all, and I didn't like it. There's a reason why the Anax mod exists for the HD800.

With the tweaks, the HD650 sounds faster, crisper, more lively, less over damped. I would not attempt these tweaks on the HD600 though. Overall, maybe a few db too much mid-bass, but everything else sounds just right. (I would ignore the roll-off past 10kHz in the FR graph, it's a measurement thing with how the microphone is angled on the measurement system.) Recordings which are a little bright like Midnight Oil Diesel and Dust are indeed a little bit bright. Recordings which are laid back like Natalie Merchant Tigerlily are laid-back, but not rolled off to shit. Taylor Swift's voice is a bit shouty, but not unbearably so. As I've said - just right.

Currently, I've got the HD650 hooked up the Theta Data III / Yggy / Zana Deux Super and have been enjoying it every night since I came back from the Bay Area meet. This is a fantastic combination that is easily end-game for most people. I know it's a little bit odd with me talking about this $300 mid-fi headphone, but I assure you this headphone is anything but mid-fi. Yes, the HD650 does belong in an obscene TOTL type rig. It's rather funny because today I received a PM:

Hey if you get a quick chance, I also wanted to hear your thoughts on the HD-650 vs LCD-3 for details. I'm hearing much, much more with the HD-650's, and it is making me think the LCD's will never offer the same presentation. The 650's seem to be presenting much more micro detail and I'm hoping I can take the LCD's to that level. Do you think it's possible with the right setup?

Here is my response:

It's funny you mention the HD-650. The latest HD-650s are really fantastic and IMO a superior headphone to the LCD-3F. The new Fazors are actually a downgrade from the older non-Fazor LCD2 and LCD3s. Yes, they sound worse. I know because I have an old LCD-2r2 non-fazor which has better transient response and faster less muddy bass than anything Audeze currently produces. The HD-650 is an extremely resolving headphone that doesn't get enough credit. Best kept secret for just over a few hundred bucks. It keeps scaling and scaling, even with a resolving DAC and amp - even up to the $7k amps that EC makes.

So I'm pulling your chain right? Nope. You guys have to remember that this is Changstar. We won't sell you guys on thousand dollar headphones if they do not perform. So before any of you guys drop serious money on headphones, seriously consider the HD650 with a good amp and a good DAC. And BTW, traditional dynamics, especially the Sennheiser dynamics, tend resolve better than most planars. They don't sound as clean, they aren't as fast, but they do resolve better. Something to keep in mind if you have Yggy.