Thanks for the input. I have a lot to learn!  

I am using i phone 4 and ipad. Since I will be running the signal through a Sony PHA-1 DAC / amplifier I am thinking it would drive the Beyerdynamic DT 880 600 ohm headphones O.K. I was advised the 600 ohm had a better sound even though it takes more power to drive it.

Thanks for allowing me to post on your site. I love this great site and recently watched Jude's interview on youtube. Great to see all the passion for great sound. I'm new to head-phone audiophile purchases but have always loved good music and can start to afford decent cans. Just bought the...