New to Headphones

[littlegiant]

I've never owned headphones. I am looking at the Hifiman HE400i, in part because of the reduced price.

I have two systems. A smaller system with a Pioneer Elite VSX-80TXV receiver/amplifier. The larger system has an Anthem AVM 60 processor, Oppo 205 player, and Anthem MCA amps. What do I do to make the headphones work (I told you I was new to headphones)? Do I need anything in addition to the headphones?

Also, I need an appropriate headphone extension cord that is 12 to 15 feet long.

One last point, I wear hearing aids because my hearing has deteriorated in the higher frequencies because of age and radiation treatments I endured many years ago. Therefore the best and highest quality headphones are largely not beneficial. Good quality at an affordable price is about all I can utilize.

Thanks for helping.