Pros: Isolation, fit, fast well weighted bass.
Cons: Honky midrange, splashy treble. Not an easy listening experience.
To start this off, i did not pay for my pair of 315. If i had payed for them the disappointment would be vast.
I have a pair of SE215 and while they are not my favourite iem, they have their place. Isolation is great, and the sound is warm and quite mid-forward and matches easy with many genres of music.
The 315 is well, not as good. Simply put.
I had high hopes on the 315, i really had. However upon first listen i though they sounded a bit strange. On some tracks like some 90s death/black metal or Bob Dylans earlier work they shine. Clear midrange and nice air and separation. Overall clarity and balance is a joy.
But on some tracks there is a honky shrill in the midrange. Almost like a shout. It´s hard to explain but i think most listeners with some experience will notice this. To name some examples: Dream Theater, Soundgarden, Incubus, Ghost are not really enjoyable with the 315 just because of that honky midrange.
If you want to monitor vocals and bass during a live performance, they will do a good job. But for a purely enjoyable listen, not so much.
I am by no means a bass-head and i do like a forward prominent midrange and i absolutely like my treble.
Oh i better say something of the overall design as well.
They have a very nice fit and good isolation. The connectors had held up well for me but i don´t remove the cables very often. The eartip selecton included should fit all users and are of very high quality.
However the Cable on the 215,315,425 and 535 is crap. It´s to long and it gets very stiff over time, even more so if you live in a colder part of the world. I have bought a third party cable for my two pairs and i would suggest you do the same. There are many to choose from and the price is about 10-15 USD.
Save your money and get the 215 if you want a pleasing slightly warm and forward sound signature. The 315 definatly have some tuning issues which is a shame. The single BA have some great potential here, but the tuning is off to my ears.