Nevertheless, I was comparing the s680 and the CAL using the same amp/DAC and player. I'm considering selling s680 because it wasn't up to my expectations and wasn't significantly better compared to the other headphones I already have. I really want to like it but the extra bass just isn't my thing.
I followed the burn-in instructions exactly as written
S680 thrives on high detail, and E17 isn't giving it.
Just because you used the same DAC/amp to compare two headphones, and one of them doesn't sound right, that doesn't mean that it's the headphone's fault.
I'm sure HD800 wouldn't sound great out of E17 either - but would anyone say that HD800 is a bad headphone because of that?
Anyway, I have tested my S680 with E17 just now (never did before), and the vocals are a bit off.
ODAC does a much better job, but if you don't want to spend ODAC money, Hifimediy Sabre DAC sounds great too.
I have just tested the asycnronous version, and it's almost indistinguishable from ODAC, at just 57$.
http://hifimediy.com/index.php?route=product/product&product_id=123
The synchronous version is even cheaper at 42$ and sounds the same (I have both) :
http://hifimediy.com/index.php?route=product/product&path=62&product_id=83
However, I still don't know how much of your problem is because of E17 and how much because of burn-in.
May be you should try to burn-in on higher volume than before, while you wait for your new DAC
Don't give up so easily, you've got yourself a really great headphone really cheap - you just need to make a small effort to unlock its full potential.
P.S. Did you also do the brain burn-in as requested in the first post?
Another member had a similar problem, until he gave his brain a little time to adapt:
http://www.head-fi.org/t/690493/the-jvc-ha-s680-s400s-and-s500s-big-brother-is-here/225#post_10126378