If you are after good sound this is all you need. There is no need to carry a portable amp. There is enough power drive my 250 ohm DT-990's with power to spare. The sound is full and lush and takes my EIM's to another lever.
I have the RE-262 and thought they were good. Matching them with the HM-601 brings out their full potential. Tighter bass, crispier highs, depth and wider sound stage. Over a very crisp clean sound.
My co workers joked around when they saw it and didn't take it a serious DAP saying it looked like it was from the 80's., However the shocked look on their face after they heard it, said everything.