[Alligator]

I have a pair of Sony MDR-7506 closed headphones and would like to get back into listening to some new music in the evening. First, I want a decent upgrade from what I have, preferably closed design so I don't bother my wife. My budget is $100-300 or so, but is flexible. I was looking at the ATH-M50S, but would like more opinions.

Second, I'll most likely listen in my bedroom where I do not have a receiver. I may listen with an iPhone/iPad. Should I also be getting an amp? I find listening in the dark when I can focus only on the music really helps me enjoy it. I will not be falling asleep with these, so I'm not worried about that. I will most likely listen sitting up. If I need an amp, which one?

I've done quite a bit of searching, but most are focused on ~$100 headphones. I want something a little better. Thanks!

 

[smashing]

Just wondering, what is your complaint with MDR-7506. It's quite a good headphone and most of the $100 headphone wouldn't be that big of an upgrade from it anyway. 
 
If you could get a cheap tube (like LD Mk3), you could then pair it up with some orthodynamic goodness, like the Fostex T50RP, which is selling at less than $100.

 

[Alligator]

Sorry, I should have clarified.  My Sony headphones are falling apart from many years of use.  The pads are tearing off and they have been abused on many, many trips.  I enjoyed them very much, except for the coiled cord and the slight lack of full range.  They were good, but not perfect.  To be completely honest, I'm also enjoying the experience of trying something new and different.
 
I'm doing the research and I've read the good reviews of the HD650's and I'm intrigued.  Although they are more expensive and an open design, I'm wondering if they would be worth it.  But then I'd have to buy the amp . . .
 
I'm on the fence about a new amplifier (I have a tube amp for my turntable and love it) or whether I should put the money in the headphones.