Update on a good inexpensive amp with awesome synergy with Grados.... Schiit Vali and RS2i. Amazing! No hiss/noise and the microphonics that people talk about are exaggerated. tapping the chassis with my nails and there is no ping at all. Sound is much better than my O2 for the RS2i.. More matured, more refined, less distortion and all the grado fun is intact!