I am a little confused on what you want. You want something that's portable(move around the room) but you also want something that's is for monitoring and mixing(sit in front of your equipment). That's kind of 2 different categories in my view.
I will give you my 2 cents anyway. I have HD580 and JDS Cmoy Bass Boost amp and UM3x, which was one of the best universals.
I enjoy them both, but HD580 + Cmoy gets much more uses because I sit in front of my computer a lot more than I spend time on transit. In fact, I don't even like wearing IEM when I walk around, sit in buses(I feel uncomfortable when I can't hear the surrounding). I have to say HD580 is really lacking power for me without the Cmoy, but I don't ever feel like I need to upgrade my Cmoy to something better. HD580 is about $150?? and Cmoy is about $60??. If you want better sound than that, you probably should move to a higher price tier headphones (such as DT880?) instead of upgrading amp. (But upgrading headphones also requires upgrading amp! Wallet crys :'(
Additionally, HD580 wins hands down in terms of convenience and comfort when you are comparing it with UM3x(or probably any other IEM). HD580 you just put on top of your head, super easy and super comfortable. IEM is also pretty comfortable but it always takes at least 30+ seconds to put on for me because I have to squish the olives and hold it in place for a while. I can probably leave HD580 for hours and IEM will need repositioning every now and then.
If you are really serious about mixing you probably shouldn't use HD580 either because it is not that neutral. But UM3x has a ton more details and is more neutral than HD580 (which makes it less fun sometimes.) I really like UM3x when I am listening some really good recordings and the details flies everywhere. In contrast, HD580 is more general usage.
Anyway it really depends on what you want your headphones to do. I am all for HD580+JDS combo when it comes to headphone that stays at the desk. If you want something portable, I would not recommend HD580. Any IEM will definitely takes some getting used to and you can make your own decision if you want to keep using it. Think realistically about your budget, and do lots of readings to try to find the best phone that fits your need. You can always sell them back onto the forum for a small loss if you found out you don't like what you hear. Good luck.
