Got these in last night.
They are bland to me. Little less bass is right. They sound very flat to my ears. There is detail in the sound but it doesn't feel like it. Like everything is slightly muted and not as responsive. They don't sound bad. They just don't sound engaging. So pretty much I guess what you heard about. They probably sound like the pro 80s with less bass. Which is funny because I thought they might sound more like the Hyper X Clouds I got for a friend that was wanted a new gaming headset a few months ago. Those Clouds didn't sound bad at all, were easy to drive, and had decent thump. The Clouds were suppose to be based on the Takstar pro 80 as well. The MDH8500 sound overall more muted, harder to drive, and slightly rolled off on bass. There is no sub bass on these though that I can tell. I will say while the mids and treble have clarity of sound (if muted clarity) the bass lacks that same clarity to me.
They do need some amping though. Compared to my SHP9500, I had to turn the volume up from 25% low gain on the mangi 2 uber to about 40% for the same volume. Not as bad as having to switch to high gain for the 600ohm dt880 though. Most other easy to drive are around 20-25% volume on low gain for me. The harder ones like the 400i are about 50-60%. So the MDH8500 are in that harder to drive range but not as hard as the 400i
Build quality and comfort are great on these MDH8500 though stock. I really don't think anyone looking for a pair of cans would be really disappointed with them. Just make sure you have a decent amp and they will sound good. A little bit of EQ to bring the bass up and all set if you prefer slightly more bass. Those that don't like that much bass I think would enjoy the MDH8500 if they want a closed set of cans that sound "audiophile" neutral.
Side note.. opened my front door this morning before work and I have two more packages sitting there. Looks like my Sennheiser HD 206 and Philips X2 came in.