WayTooCrazy
Headphoneus Supremus
Not making this easy lol! At the end of the day I feel like most audiophiles would say you can't go wrong with the HD6x0 line but Sine is still tempting for the value.
At the current sale, it is very tempting. If you want some isolation and portability, go with Sine. If you want something that scales, is open and can be used as reference for future purchases... go HD6x0 (my preference being HD600). This is the reason I got them. Now my future purchases will have to be less expensive, or sound better than the HD600 or they don't make financial sense to me. Unfortunately, that would mean going back up to the LCD-2 I sold due to weight.