SE-MJ591 Sound Quality and Comfort
Before I go any further, let me say that the Pioneer SE-MJ591 headphones are, without a doubt, the best headphones I've ever experienced. Bar none. The Pioneer SE-MJ591 headphones feature a 40mm (1.5") aluminum driver. They have an impedance of 32 ohms and sensitivity of 108 with a frequency response spec'ed from 5Hz to 40kHz. I tested the SE-MJ591s with the Rives Audio Test CD 2 and found that, of the spectrum that I could test/hear, the Pioneer's sounded very smooth and clear. Nothing seemed out of whack or even a little askew. The bass wasn't the strongest but it was there. If you are looking for headphones that thump, these aren't them.
One thing you'll find with all high-end speakers, particularly headphones, is that they will reveal things that you never noticed before. Like how bad your MP3s sound. That's right, 128-bit compression might be fine for your car but it is not going to sound great in your SE-MJ591 headphones. All the clipping, all the harshness, all the distortion will be evident. But these are headphones designed for audiophiles. They aren't going to have compressed audio (I know I don't...mostly).
Pioneer markets their SE-MJ591 headphones for critical listening and I wholeheartedly agree. These are headphones that will show you all the flaws in your music. You'll find yourself reevaluating your music collection. If you are like me, you'll go to your music app and put together specific playlists just for your SE-MJ591 headphones. Because not all of it will sound as good as you remember. These headphones are revealing and unforgiving.
But when they are paired with a well-recorded track, you are going to find yourself wanting to just listen. When I first started my tests with the Pioneer SE-MJ591, I actually stopped what I was doing and paused the playback. I said to myself (out loud, mind you), "I've never heard that before!"
I know, it is trite and a stereotype in audio reviews to say that you heard something that you never heard before, but stick with me.
It was a recording with a pan and I had never noticed the pan before. So I jumped up and grabbed both of my reference headphones (Denon AH-D1000 and Audio-Technica ATH-M50S) to compare. Sure enough, the pan was there but it was much less noticeable. Switching back to the Pioneer headphones showed just how much more clear and distinct the pan (and many other things) in the recording were. I heard much more than I did with any other listening device. Part of it was that I was paying attention but, more importantly, the SE-MJ591 had much more depth than I was used to.
This leads me to my favorite thing about the Pioneer SE-MJ591s - the imaging. I've sat in a room with a couple of $20k a pair electrostatic speakers pointed right at me. It is an experience I'll never forget. This sort of speaker can make it sound like the music is coming from inside your head. While the Pioneer SE-MJ591s don't recreate that experience, they come as close as I've heard. The imaging on these headphones are as good as I've heard from any set of headphones or speakers outside of electrostats. Everything about the sound quality of the SE-MJ591s is absolutely top notch.
And here we come to one of the two most important factors when considering headphones. Along with sound quality, comfort is important for whether or not you'll use and enjoy your headphones. And here is where the Pioneer SE-MJ591s fell down for me. I've owned every type of headphone from over-ear to on-ear to in-ear. Each have their advantages and disadvantages and I really don't care which option a manufacturer goes with.
What is important is that they are comfortable.
The Pioneer SE-MJ591 just weren't for me. The ear pads were soft to the touch but the entire headphone, when place on my head, pressed a bit too hard. The padding on the top of the band (the part that would rest against the top of your head) was hard to the touch and even harder when I was wearing them. I could extend the band so that the pressure was taken off the top of my head which made it better but then the headphones felt less secure.
The real problem for me was the pressure on the ear. Even though the ear pads were soft, the pressure on my ears was so strong that it caused discomfort immediately and pain after any sort of extended listening session (I couldn't make it through an entire album without taking a break). I don't believe I have an overly large head (ego notwithstanding) so I don't think that was the problem. It may also be that, within time, they will loosen up. But in the few weeks I've tested them, they haven't. At least not appreciably. For a new buyer, I would highly recommend you try them on first.