I'm looking to add another open headphone to my collection. I like my DT660 (32 ohm) very much and bought it because it was closed. I am surprised by how much sub-bass it has. I likee. I'd like to find an open can with that kind of sub-bass on a $500 budget limit. I thought maybe an open BeyerDynamic might be the ticket. I've been reading a lot about the HiFiMan HE-400 and that might appeal, too. But, here's the spoiler alert, I'm a Grado man so you know I likes my brites. These are the two I've narrowed it down to because I've heard examples of both brands, DT660 and HE-5LE.
What do you think? Am I on the right track? Suggestions/advice?