Prior to the Amperior my main portable headphone was the Sennheiser HD 25-1, which I kept for ten years and really enjoyed, especially with the velour pads.
I sold my HD 25-1 about a week after getting the Amperior and have never looked back.
The Amperior is a clear step up sonically and is a more luxurious headphone than the HD 25 in terms of aesthetics, physical comfort, and sound. The Amperior's remote control/mic works very well and is proving to be very useful, too; it's a welcome bonus for people who like to use headphones with their phone.
Overall, I find the Amperior very easy to enjoy and highly recommend it!
Kudos to Sennheiser for the Amperior, an excellent addition to their great headphone range.