panteraMetal... get the 500's. That's all there is too it. I'm actually glad they don't render my 650's obsolete because that means I have an excuse to keep them
They do compliment the 650's perfectly though.
also, you're right. The highs are only fatiguing when A/B'ing with the 650's because the 650's have such gentle treble in comparison.
Also, I've been burning them in with Daft Punk and the highs are already taming down a bit. They still have that brilliant sparkle though.
Here...
Try listening to this:
at about 1:26 the chimes show up. On the 650 they're smooth, recessed, whatevs. on the 500's... oh goodness. you have no idea what you're missing.
The mids...
I couldn't give you a straight answer. The mids on the 500's are excellent, far better than they have any right to be. They're just not as prominent as the mids on the 650's and they miss that... that
edge that makes the mids on the 650's so dang addicting. I blame the titanium drivers on the 650's.
Also, the bass on the 500's is better. Period. It goes deeper, hits harder, it's cleaner, it's more detailed, and it's just... better.
But don't think that they're V shaped. They're actually beautifully balanced. The best way to describe them would be:
dynamic. Everything is there. Nothing overrides anything else. You don't have bass bleeding into your mids, you don't have mids drowning out treble, you don't have sibilance, you don't have distortion. Everything is there, and it works, and it's absolutely glorious. I've been shuffling through my entire music collection (over 4 months worth of music) when I'm not burning these in and I haven't found a single song they can't handle brilliantly. These are everything I've been looking for in a pair of portable headphones. They cover all the weaknesses of the 650's while retaining the strengths.
And they're still not burned in yet :3