I have a pair of hd 650's I use a penguin {altoid} amp with them and they sound phenomenal... Not sure what the difference is between the 650 and 700s... but the 650s sound good with no amp too on my iphone, BUT with the amp forget it, the bass is alive, they are super detailed, very very nice set of muffs.... I wish I got the rechargeable amp because 9v's get tough to keep around, but they last a long time, I forget it on is my main issue... And I finally broke down and bought myself a decent jumper cable to go from my phone to the amp and I wrap an elastic around them so they dont unplug each other... Not sure what you will be doing while wearing them, I use them when shoveling snow, running, working out, outside {which could be anything from jungle gym to flipping tractor tires}, ect and the stay put and comfortable...