I have a K618DJ and ordered an O2 amp with ODAC.
My question is simple.. will I hear the difference with and without the amp.
I have a test K701 lying around for few days so I might upgrade headphones.
I don't know much about the K618DJ, but I have the Q701s (which are known to be very similar to the K701s), and I have the ODAC+O2 combo. If the K618DJ are anything like their higher numbered versions, I can tell you that it will be a world of difference with the ODAC+O2.
That being said, the K701/Q701 and K702 are known to be very hard to drive, so you will definitely notice the difference if you try it out with the K701s you're going to be testing, regardless of your experience with the K618DJs.