Oh gosh I just finally had a listen to the MDR-7506... I can tell why they are used for mixing and mastering! But sadly, I got a headache within 3 minutes of listening. The treble is elevated, and makes details pop out, but also made vocals sound very thin with no body behind them. It works for some music types, but "answer to the master" by def Leppard was not enjoyable lol. There's a string of cymbal crashes that had me reaching for my volume controls to turn it down... When I EQ'd the treble down, it was an enjoyable experience. Comfort is above average, borderline amazing, and the build was a bit better than my K240's and UE6000. I'd say on par with my ATH-WS77. For listening to like... Electronic music it was good... Just do not listen to rock lol.
You should've bought Senal SMH 500/1000 (especially SMH 1000 if you want detachable cords)
Senal SMH 500/1000 is basically a sonically pain-free alternative to V6/7506.
I own the SMH 500, it only cost $39.
I took out the pads for cleaning and I noticed that the whole driver is covered with this paper-cloth hybrid material. I think that material covering the whole front driver is what causes SMH 500 & 1000 to sound smooth & pain-free compared to V6/7506.