I'd like to buy some new headphones. I'll be using them to mix and record my own stuff. That will probably make it a closed model. Then the guy in the store says to me that mixing is preferably done with a half open model because they sound better. Is that true? I used to have and like a Sennheiser HD250. That one is all worn down. I have listened to a couple of headphones today. Beyer DT770 Pro (closed): I found the lows too much of a singular blob. Beyer 990 Pro (half open): better, but not suitable for selfrecording. AKG K240 closed: better but are they better than e.g. Sennheiser HD280 or HD25? Are all mentioned even professional headphones? Do I need a closed or a half open model? Both? Which way to go when I liked my old HD250 so much?