Bummer about the 'NC always on'...makes it a non-starter for me. That said, I saw some new ones recently for $119 but they're back up to $139. I expect they'll be at $119 or less for Black Friday. If so, I'll probably buy them, listen for a few weeks, and them pass them on to my son like I did the Solo 2's.
Amping for the headphones listed? They all work quite well out of my LG V20 phone (no external amp needed)...even the 250 Ohm DT990. Do some of my Beyers and Senns scale with better amps? Yes. Can't say I got that impression of the Solo 2's.
BTW, to my ears the Amperiors are much better than Solo 2's. I'd give a slight edge to the M80's and rate the FC300's on par...both at half the price!
Which brings me full circle to value. I look for high-value audio that entertains me and keeps me interested. Those in my list do at their price points. The Solo 2's didn't...hence, they're gone.
Might have been lucky on the D600's. I spotted them at Best Buy when they were clearing them out and posted them on the Deals Discussion Thread -- a bunch of us got them.
Lastly, these types of deals are pretty normal and are really what make the Beats brand a poorer value -- even when you ignore their build quality issues.
I've gotten AKG K518LE's for $27, ATH-WS55's for $30, and Sony V6's for $60 to name just a few other high-value cans. Didn't buy them but Urbanite XL's have recently gone for $79...and the list goes on...