I dragged my friend to Audio46, who also mainly uses mdr7506, plopped the Sundara's I was trying on his head, and his reaction was "they sound like headphones". The same headphones that sounded so amazing and immersive to me didn't even make him flinch.

My point is that a headphone that universally "wows" doesn't exist. And unless you know what to listen for, diminishing returns start way cheaper than you may think. I guess maybe blasting him with soundstage with a k612 and then putting on Yosi Horikawa might work, but I don't think it would change his worldview. Especially if he prefers a more intimate sound (like me).