When you said you like the IM70, did you mean you tried it? The IM70 can be a bit fussy to wear so if you actually managed to demo it and liked it then that'll make things slightly easier.
Also, when you talk about spending "6500" or "7500", what currency are you talking about? Seems like it might be Japanese Yen you're talking about there.
The Shure SE215 is not fragile by any means, it is fairly durable. However, the nozzles (ear tip holders) have been known to snap off if you're not careful. They're pretty thin and may break if you handle the earphones roughly while changing ear tips. That said, the cable on the Shure is one of the best around.
Meanwhile, the IM70 cables, while not bad, do have issues. The ear guides have been known to snap with people who treat their earphones with less care. The E40 is very much the same.
Assuming your budget is at US $99, I think I'll personally not consider the M6 Pro and focus between the SE215, the IM70 and the E40. All three have pleasing sound signatures, all are roughly the same price (depending on where you get them from), all are relatively durable, and all three are good in their own right. I'm not including the Vsonic GR07 in this list because its sound signature isn't always the most agreeable with people, it's pretty sibilant.
I can't tell you which is the 'best' I've heard, because best is subjective. What I can do is elaborate on each in more detail and compare between the three based on my personal opinion.
1) Shure SE215 (original):
- The most durable overall
- However, nozzle has been noted to snap off when handled roughly
- Sound: focus on mids (guitars, vocals, brass, etc), little bass and treble emphasis. Very smooth and pleasing, albeit a bit boring sounding.
- Also comes with the best selection of (and most practical) accessories
- Recommendation: If you aren't particularly bothered with taking of your earphones (e.g. keeping them in a case after use), then the SE215 are the ones most likely to hold up well in the long term. Shure also has excellent customer service based on customers' feedback.
2) Audio Technica ATH-IM70:
- While the ear pieces themselves are pretty durable, cable ear guides have been known to snap when handled roughly (i.e. not storing in case when not in use)
- Sound: very smooth and liquid mids, slight treble roll-off, thick but not overbearing bass. I tend to recommend the IM70 the most at its price because most people I know find it very agreeable and easy to listen to, being very non-fatiguing yet retaining a good amount of detail. It is more detailed sounding and has more bass than the SE215, but the SE215 sounds cleaner and more 'accurate'.
- Recommendation: If you can take care of your IEMs, the IM70 will last a good long while, and will provide a good balance between relaxed and engaging sound. As I've said, the IM70 is my personal favorite at this price.
3) Audio Technica ATH-E40:
- Same comments about cable as the IM70. While they use different connectors, the build of the cable is pretty much identical.
- Sound: The most energetic out of the three. If you want more engagement and excitement in your music than what the IM70 can offer, the E40 is clean, controlled, and detailed. The E40 also has the most bass out of the three. Its only downfall is that it can sound very slightly harsh or splashy at louder volumes and with poorly mastered tracks.
- Recommendation: If you tried the IM70 and found it too relaxed, the E40 could be a good alternative.
That's just my opinion between the three. If you're very concerned about sound and durability, I wouldn't concern myself too much with how the earphones look. But that's just my personal opinion.
If you have any more questions, feel free to ask more.
