The only other IEM I've ever tried is the Shure SE425. The SE846 has not only better bass (obviously) but I confirmed that it has better treble and mids. The SE425 sounds downright muddy relative to these. The treble is very slightly rolled off on the SE846, I think, but that's subjective so it might be just right for you. The bass on these is like everyone says, tight, deep, natural and undistorted. But it's not at all like beats or other boomy headphones. Play a bass heavy track and you'll hear it with quality, but it doesn't inject bass where it doesn't belong and it is not excessive. It also sounds nothing like a proper subwoofer; it's no where near that impactful and strong (you can feel a subwoofer in your body) so let's dispense with that bit of marketing right now. However, it delivers bass similar to what you would expect from a quality neutral full sized headphone, with very little distortion and very cleanly. It was unusual to hear that sound from a tiny IEM; at first I found it kind of disturbing, sort of like how you would feel if you saw an ant carrying a rock on its back, lol.
The above was with the blue filter, which leads us the reason why this is one of the greatest headphones ever made: its filter system. When I moved to the white filter, the bass seemed much lower. I say seemed, because the manual says that all the white filter does is raise the volume between 1khz and 8khz by 2.5db, so it shouldn't affect the bass. Any way, that extra treble sort of drowns out the bass I guess. After about 3 hours on each, I think I'd like something between the white and the blue (can we get a light blue filter Shure?) But since that's not available I'll spend most of my time with the white. Regardless of what you like, the three filter thing is a very cool innovation by Shure which deserves praise. The only problem with it, is that you might find yourself constantly wanting to switch, to hear how the other filter sounds with a particular song, and I'm guessing I'll be losing/breaking these filters at some point from all the changes, lol. Not sure what the replacement cost is. But this feature, which will probably be copied by others, deserves a 1 star boost. It's like getting three headphones in one.
One last comment on the bass -- it's very DAC (and amp, if your amp adulterates the signal) dependent. I say this because the bass output is much much higher when I plug this into my LG G Flex phone, than it is when I plug it into my Note 2 phone. The Note 2's DAC is much brighter but that causes the bass to almost disappear. If you're not hearing bass, switch DACs by trying it on another phone, or your laptop.
As far as fit, if you buy a professional tip from Comply, I don't think it's possible to get an improvement by purchasing a custom molded sleeve. Shure IEMs + comply tips go deep into your ears, they are comfortable and they fit every nook and cranny of your ear canal. Just get the right size. I have never tried a custom made IEM but I would not be surprised if they didn't fit as well as Comply tips. The tips supplied by Shure are not as good for comfort or isolation, and I will never use them, but you can buy Comply tips for $20 which isn't much relative to the price of these things.
Moving on to the isolation. First of all, Shure is misleading customers when they claim that the SE425 and SE846 provide the same isolation (its website states that both "provide up to 37 dB of isolation" without distinguishing between the two). The SE425 with professional Comply tips is like wearing hearos ear plugs. A car can go by you at 35mph and it'll sound like a very light whispery vroosh. You can't make out what people are saying, even if they're right in front of you. With the SE846, the car is louder and you can hear people's voices a little better. If you look at the innerfidelity charts, they confirm that the SE425 isolate better than the SE846. At first I was annoyed by this slight downgrade in isolation, but then again the isolation of the SE425 might be dangerous. It's kind of odd walking next to a busy street and barely hearing anything. Very risky if you're bicycling or something. Plus, once I find where the noise is leaking into the SE846 I can put tape over it or do another mod (I think the noise might be coming in from that mechanism they use to let you change tips, perhaps it needs a gasket that I can easily craft). I was going to take off 1/2 star for the downgrade in isolation, but now I'm not sure. I think the Etymotics isolate sound excessively and are unsafe, but I'm not sure whether the SE425 or SE846 have it right. Edit: I created a gasket out of about a 2mm thick slice of a hearos earplug (when compressed it's about as thick as a hair), and inserted it between the base and the screw you use to attach the filter to the base. After doing so, I can no longer hear people talk in front of me; I think the SE425 might still have a tiny bit better isolation but I would have to do careful listening tests to be sure.
Getting back to the sound quality, the SE846 still generally doesn't sound better than a solid $300-$500 over the ear headphone. It is NOT EVEN CLOSE to the sound of a flagship over the ear. If I were to start comparing this to the HD800 I would trash this a hundred ways, relatively unresolved and sloppy bass, relatively unresolved treble, treble roll off, lack of spatial imaging, I could go on and on. The first company that makes an IEM that is objectively indistinguishable from an HD800 in blind tests will make a fortune. These are only worth it if you listen to music with a ton of ambient sound that you need to block out or if you don't like the looks of a big headphone; otherwise always buy a full sized headphone. At the same time, it's in another universe relative to the SE425. Those sound awful once you wear the SE846. I really need to try the IE800 (which I didn't buy because it doesn't accept Comply tips, and it has much worse isolation than the SE846 according to the innerfidelity charts) to compare the two [Edit: I purchased and reviewed the IE800 which you can find in my reviews]. But since the reviewers who compare this to the IE800, JH13/16 etc. and other $1,000 IEMs aren't sure which is best, I think this is about as good as it is going to get with IEMs -- which is disappointing.
One other observation is that these are louder than the SE425. With one volume bar, this is like having two volume bars with the SE425 (I checked with a decibel meter, measuring dbA slow). Similarly, with two volume bars, this is like having three volume bars with the SE425. I hear Shure didn't do this on purpose to fool customers with the "louder = better" trick. But please keep this in mind. These have virtually no resistance and they put you at greater risk of hearing loss if you're not careful with the volume. But also keep in mind that the increased bass response of these might be affecting dbA measurements; I would have to dig into the dbA formula to confirm.
Due to the high expectations from a $1,000 price, this isn't quite a 5 star product, but I'm keeping them because when a song with bass comes on, I want to hear it, rather than hear that lame tapping sound the SE425 calls bass, and overall I think they deserve 4 1/2 stars. Add the 1 star boost due to the filter innovation and it's 5 1/2 stars (capped at 5 stars).
The above was with the blue filter, which leads us the reason why this is one of the greatest headphones ever made: its filter system. When I moved to the white filter, the bass seemed much lower. I say seemed, because the manual says that all the white filter does is raise the volume between 1khz and 8khz by 2.5db, so it shouldn't affect the bass. Any way, that extra treble sort of drowns out the bass I guess. After about 3 hours on each, I think I'd like something between the white and the blue (can we get a light blue filter Shure?) But since that's not available I'll spend most of my time with the white. Regardless of what you like, the three filter thing is a very cool innovation by Shure which deserves praise. The only problem with it, is that you might find yourself constantly wanting to switch, to hear how the other filter sounds with a particular song, and I'm guessing I'll be losing/breaking these filters at some point from all the changes, lol. Not sure what the replacement cost is. But this feature, which will probably be copied by others, deserves a 1 star boost. It's like getting three headphones in one.
One last comment on the bass -- it's very DAC (and amp, if your amp adulterates the signal) dependent. I say this because the bass output is much much higher when I plug this into my LG G Flex phone, than it is when I plug it into my Note 2 phone. The Note 2's DAC is much brighter but that causes the bass to almost disappear. If you're not hearing bass, switch DACs by trying it on another phone, or your laptop.
As far as fit, if you buy a professional tip from Comply, I don't think it's possible to get an improvement by purchasing a custom molded sleeve. Shure IEMs + comply tips go deep into your ears, they are comfortable and they fit every nook and cranny of your ear canal. Just get the right size. I have never tried a custom made IEM but I would not be surprised if they didn't fit as well as Comply tips. The tips supplied by Shure are not as good for comfort or isolation, and I will never use them, but you can buy Comply tips for $20 which isn't much relative to the price of these things.
Moving on to the isolation. First of all, Shure is misleading customers when they claim that the SE425 and SE846 provide the same isolation (its website states that both "provide up to 37 dB of isolation" without distinguishing between the two). The SE425 with professional Comply tips is like wearing hearos ear plugs. A car can go by you at 35mph and it'll sound like a very light whispery vroosh. You can't make out what people are saying, even if they're right in front of you. With the SE846, the car is louder and you can hear people's voices a little better. If you look at the innerfidelity charts, they confirm that the SE425 isolate better than the SE846. At first I was annoyed by this slight downgrade in isolation, but then again the isolation of the SE425 might be dangerous. It's kind of odd walking next to a busy street and barely hearing anything. Very risky if you're bicycling or something. Plus, once I find where the noise is leaking into the SE846 I can put tape over it or do another mod (I think the noise might be coming in from that mechanism they use to let you change tips, perhaps it needs a gasket that I can easily craft). I was going to take off 1/2 star for the downgrade in isolation, but now I'm not sure. I think the Etymotics isolate sound excessively and are unsafe, but I'm not sure whether the SE425 or SE846 have it right. Edit: I created a gasket out of about a 2mm thick slice of a hearos earplug (when compressed it's about as thick as a hair), and inserted it between the base and the screw you use to attach the filter to the base. After doing so, I can no longer hear people talk in front of me; I think the SE425 might still have a tiny bit better isolation but I would have to do careful listening tests to be sure.
Getting back to the sound quality, the SE846 still generally doesn't sound better than a solid $300-$500 over the ear headphone. It is NOT EVEN CLOSE to the sound of a flagship over the ear. If I were to start comparing this to the HD800 I would trash this a hundred ways, relatively unresolved and sloppy bass, relatively unresolved treble, treble roll off, lack of spatial imaging, I could go on and on. The first company that makes an IEM that is objectively indistinguishable from an HD800 in blind tests will make a fortune. These are only worth it if you listen to music with a ton of ambient sound that you need to block out or if you don't like the looks of a big headphone; otherwise always buy a full sized headphone. At the same time, it's in another universe relative to the SE425. Those sound awful once you wear the SE846. I really need to try the IE800 (which I didn't buy because it doesn't accept Comply tips, and it has much worse isolation than the SE846 according to the innerfidelity charts) to compare the two [Edit: I purchased and reviewed the IE800 which you can find in my reviews]. But since the reviewers who compare this to the IE800, JH13/16 etc. and other $1,000 IEMs aren't sure which is best, I think this is about as good as it is going to get with IEMs -- which is disappointing.
One other observation is that these are louder than the SE425. With one volume bar, this is like having two volume bars with the SE425 (I checked with a decibel meter, measuring dbA slow). Similarly, with two volume bars, this is like having three volume bars with the SE425. I hear Shure didn't do this on purpose to fool customers with the "louder = better" trick. But please keep this in mind. These have virtually no resistance and they put you at greater risk of hearing loss if you're not careful with the volume. But also keep in mind that the increased bass response of these might be affecting dbA measurements; I would have to dig into the dbA formula to confirm.
Due to the high expectations from a $1,000 price, this isn't quite a 5 star product, but I'm keeping them because when a song with bass comes on, I want to hear it, rather than hear that lame tapping sound the SE425 calls bass, and overall I think they deserve 4 1/2 stars. Add the 1 star boost due to the filter innovation and it's 5 1/2 stars (capped at 5 stars).
