One of the questions was will they even work. Yes, they WILL work. It won't the absolute best sound you would ever be capable of getting out of a 650, but they WILL work. I don't agree with those that say they sound fine, I think maybe those people haven't heard them at their best. But I think...

Okay, thanks. (I thought it was just me.) Wearing the LCD-2s does take commitment. If you're happy with the 598s stay with them. They're highly regarded around here. My old 595s were my "go to cans" for just about everything. I''m hoping my 598s will take their place.

And you, as well. If you have LCD-2s why are you wanting more? They're fine headphones.

I know, I know. I agree with everything else iancraig10 said, but my mileage varied on this one. It's a tossup between the 650s and 600s. If you like bass the 650s are definitely bassier than the 600s and both are better cans than the 598s, but the 598s are nice, just not quite the same level.

If you like bass, go with the 650s. I may be in the minority here, but I think the 598s may have as much or more bass than the 650s. But keep in my mind I JUST got my 598s.

Sorry, I'm not much into closed. Other than that, for warranty, Koss can't be beat. My son REPEATEDLY sends in his KSC-75s and they keep giving him new ones. My Porta-pros have held up well for years, but I don't worry about them because I know if they day ever comes, they'll replace them. I...

Yes. I agree with everything iancraig10 has said. I have the 650s and sometimes wish I had the 600s. Hope that helps.

What do you listen to and where do you listen to it? Do they need to be portable? Open or closed?

Yes.

Are you open to IEMs or do you want on or over the ear headphones?  

I happen to love the X10s. I think they have some things over my SE535s. They're more fun and they hit harder. Drums are fantastic with them. Yeah, the bass is not any where up to the 535s, but they are very enjoyable. You said they seemed flimsy. I suppose so. They are very small and very...

Keep them in your ears!

There's not a price point where you need an amp. It's all up to you. Some headphones really do need an amp, some don't, that's the sensitivity and impedance issue. Cmoys aren't useless, but they are limited. I would say it's best to go for the most you can afford, it will save you upgrading...

They're open, so they leak a LOT of sound. A LOT. Someone across the room can hear it if you have it a comfortable volume.

I have an iphone 4 and HD650s, it's not that bad. There's plenty of bass, granted it's not the best in the world,an amp would improve it by cleaning it up. But the frequencies are there, just not as tight as it can get with a good amp. As far as volume, it gets loud enough to listen to but...