Hi All,
I've had a set of 1964ears quads for a week and thought I'd leave my impression for those considering buying. My perspective is a bit different from many here as I am not as experienced as many of the audiophiles and artists on this site.
I'm a music fan who likes everything from Classical and Ambient, to Industrial and Punk, and all of the great stuff in-between.
I am an architect and designer, listen to music in often busy environments where I need silence to work well. I fly frequently and like to block out the noise on the plane. I also like to immerse myself in my music collection and block out the world when I do it. Because of this my last set of phones was a set of Noise Canceling Bose QC15s.
The QC15s are uncomfortable, get hot and sounded decent to me but I wasn't blown away. I needed an alternative and quickly found out about custom IEMs. Most of the prices were way out of my range $1000-1500 for anything good and I wasn't impressed with the idea of buying a single or dual driver IEM. 1964ears made a good pitch and the reviews here such as EricP10's swayed me.
I ended up with a nice set pictured here for $724 for the full deal including advanced art, recessed sockets, extra case and impressions. Significantly less than anything close to the specifications and range of the quads.
I had some difficulty getting them in at first. If you haven't worn customs before it will take you time to figure out how exactly to get them in and out quickly.
The sound when compared to what I was using is night and day. Amazing, detailed, no distortion that I can discern, insane amounts of bass, lovely mids and clear and crisp highs. I'm basically in love here. I tried putting on my QC15s to hear the difference after a few hours with the quads and immediately heard how just plain awful those phones are. I guess you get what you pay for and $300 bucks ain't nearly enough.
I have MP3s in my collection that range from 320 to192KBps. I'm easily able to notice flat areas in lower quality MP3s that you cannot hear with a cheaper headphone. I did find however that using the 10 band EQ with
PowerAmp (on my android phone) made it easy to improve the sound of the lower quality tracks to be quite enjoyable. I'll have to have a go with some of the iPad equalizers to see how they fare as well. I tend to stick to my android for music as it seems to sound better overall even without an EQ than my iPad. If your collection is not all high quality don't let it hold you back. The Quads still make your low quality MP3s sound amazing with a bit of EQ.
If you listen directly to a CD or use Flac you'll really uncover the true power of the Quads. There is simply no comparison when listening to non-lossy formats. I can see that in the future it's going to be all 320KBps+ or Flac for me. This is music how it should be, you can hear the texture of Johnny Cash's calloused fingers on his guitar strings and the crackle of burning paper as Tom Waits takes a drag off his cigarette between notes. A great recording is a joy to hear with these phones.
A lot of people talk about the bass of the Quads and it's no exaggeration. I used Spotify to try out some of the sub-bass tests that car freaks use to see if they can blow their doors off their cars. The Quads didn't even flinch at this and not a hint of distortion was to be found anywhere. Just insane clear perfect bass. Even at the lowest volume level the bass is clear and full sounding. This is understandable as the range on the Quads goes below the 20hz that the human ear can actually hear. These are not headphones that require you to turn the volume up to hear the different ranges of sound.
Noise isolation is fantastic and better than noise cancelling headphones. All the better that the feeling of pressure that is added by anti-noise is gone. I can listen to these without fatigue and they really block out everything. No batteries required. If you are searching for peace and quiet, get a pair of custom IEMs. I see noise cancelling technology as second rate after trying customs.
1964ears customer service is great. They answered all my silly questions quickly and were polite and informative about it. Nothing but love for this company.
Hoped this helped some on the fence with making a decision. Without a doubt, I'm a convert.
if you know what I mean. So I'll ask you guys some questions later on about the fit. 
