I'm sure it's just our own subjective differences. I'm using the stock marshmallow foams on both and no matter what I play, the IO beats the MD+ on clarity and presence. Listening to cello, the strings have a nice texture to them. The MD+ sounds softer here. Same with electric guitars. The IO gets the harshness just right where the MD+ smooths it out a bit too much. Sure it's easier on the ears but when a track calls for some screaching licks and distorted guitars, I want them to be screachy. The track "Do You Remember Me" by Santana is a good example of this as you can his guitar clearly distorting (purposely) and the IO really nails this.The MD+ softens this a bit too much for my personal taste. I just really prefer that extra energy and zing for certain genres of music, apparently. I do. I can pop them in and give them a listen and share some comparisons for you. Fair warning, the 846 is one of my fave all BA setups and one of the few I still listen to with some regularity. But I'll try my best to be agnostic in my thoughts although I'm pretty sure how that two will stack just from memory (I've had my Shure's for ages at this point).