Need Help buying headphones and head amps

My nephew is looking for quality headphones and a head amplifier for listening from his MAC computer. I know very little about headphones and head amps so I need some recommendations. After some research, I found the Sennheiser HD 650 Headphones and also the Grado GH1 headphones. The IFI - MICRO IDSD DAC also looks very interesting but I do no know. He will probably run a USB cable from the MAC to the head amp (any other suggestions?).

Does anyone have any suggestions for a high quality headphone and a head amplifier? Let’s assume a budget of $1,000 or less for both items. Any suggestions would be appreciated.

My plan is to give him 2-3 suggestions for each item and will then suggest he visit a dealer for listening and additional help. Where should he go in the downtown Chicago area for assistance? He needs a dealer that will help him make these decisions. Of course, purchasing items on line is also an option if someone suggests something. Thanks..
in chicago/evanston/hinsdale audio consultants would be a good place to audition heapdphones and amps--they have alot of grado and sennheiser at different price ranges
Head Fi is a great source of information but is a bit overwhelming, there is a lot of info out there. It takes a while to get used to it and also the tenor of the conversations which tend to be a younger age centric- than what you encounter on Agon.
What's hot right now is a tube amp from a company called Garage1217, the model is called a Project Ember. It has a feature that is not seen with speaker amps, in that you can roll almost any tube you want in it.
I have been using Sennheiser HD700s for headphones and can recommend them to my generation of speaker listeners. They are well balanced, but younger people seem to crave more pronounced bass, making the HD 650s popular.
The advice promoting auditioning is always sound. The Ember and the street price for HD700s comes in under a grand but just barely. Also there is no DAC with this set up.
Sennhesier(laidback) and Grado(forward) are polar opposites sound wise and in what amplifiers they pair well with; however both fall toward the warm side of things. My preferred brand is Ultrasone and I'd make sure to get them on the audition list for another data point(brighter sound.) I've been out of the headphone market for some time but I would recommend the site I started my audiophile journey with back in 2008, Head-Fi.
Running Senn 600 from Schiit Asgard 2 using Dragonfly2 USB DAC out of my Macbook Air.

Definitely well within the budget and sounds pretty good to me. I'd recommend upgrading the Senn 600 cable, however.

Cable Company, as Zd mentions, will lend headphones. Schiit has a 15 day return though there is a restocking fee. Music Direct has a great 60 day return policy...could get the Dragonfly there or at Audio Advisor (AA has a 30 day return).

You have received some good tips from earlier posters. Hope your nephew finds something he enjoys.
don't forget check out sony mdr7506,they are studio monitoring headphones,pretty cool sounding.Not so expensive ,but they give true sound.Using beyerdynamic a1 amp with them and grado ps1000.For quality sounds also important DAC in this chain