[Viperman5000]

I'm 98% sure I want to get these headphones. I already have a pair of Senn HD595s that I've had for some time now, I just want a nice pair of closed cans.

Now my question: I use my cell phone (Droid X) to listen to music since my iPod died on me (I have to send it in still). In the meantime, will my phone have enough to power the M50s?

 

[TMRaven]

Yes, they do.  Would you be using the closed cans for portability?  In my opinion the M50s are borderline too big for that, and their tight clamp combined with the pleather pads makes for fast sweat build-up-- not something ideal for portable wearing if you're out and about.  

 

[BotByte]

M50 runs at 32ohms, your HD595 run higher I believe.
 
32ohms is what a portable can needs, so yes, you can without a problem.
 
Just to be sure, there is a deal on Spectrum Audio for Shure 940 for $209 (add to cart)
These would be a spectacular closed can, mile above M50's. They don't need an amp also, but will benefit from one also

 

[Viperman5000]

Less "out and about", more of a "traveling/sitting at work" kind of portability. I've also read that the clamp can be stretched out using some books.

Also like above, I've had the 595s for a while and I figured they couldn't be too much bigger than those.

 

[BotByte]

M50's and 940's are good for portable because of the fold flat cups that lay on your chest when around your neck.
 
But carrying in a bag to somewhere, try a true portable like Portapro if you want to stow them away. Fullsized cans go on head or around neck, not in the pocket.
 
HD5xx cans are made NOT to be portable. Horrid portables.