These are now going to be my 3rd set of HD650's

Prior to the HD650, I've been using AKG K701 (7 bump headband, made in Austria example)

I do have some moderate experience of the sound presentation. Having owned a few HD650's in the past.

After doing some quick research on Google. My HD650 appear to be a later made example. The outer/inner box is no longer silver, both are now black. The units/frame from inside (seen through the metal grill) is now silver. Plenty chat about it over on Head-Fi.

The HD650 is an absolute sumptuous sounding headphone, that doesn't over hype the spectrum. You get a nice even handed balance through the midrange and top. Bass is well extended, and god damn goes down deeeeep!!

What I also find interesting, is that the HD650 (being 300 ohms), is more easier to drive than the K701 (62 ohms) Both headphones have over 100 dB sensitivity.

There are some people that go around saying, the HD650 is a tad warmer sounding than the HD600.... Well they're bloody right, and I believe in the such claims.

The older brother HD600 to my ears, just sound a tad more realistic and leaner. There's really not a huge difference between the two brothers, in my opinion.

S.