I added a Little Dot i+ tube amp to use with my Grado sr80i's. While the Grado's didn't need the amp, it was kind of fun. Tube rolling and swapping out op amp's on the LD i+ can change the sound up quite a bit.I sold the Grado's after getting a great deal on ATH-m50's and I find the amp actually does more for the m50's. For lack of a better description, it opens up the sound more. It didn't have as dramatic an effect with the Grado's.