The amp section is okay its not great. I would rate it 7/10   The DAC section data streamed from a computer USB is much better. I would rate it 8/10   Computer USB -->E17(DAC) docked with E09K with lo-bipass on is the best quality. I would rate it 9/10

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...

I own variety of more expensive IEM however these have to be my favorite. This is mostly due to the huge sound stage which sounds like a full size over the ear headphone.   The highs are crisp clean with good detail and without sibilance. The mids although slightly recessed still have good presence. The vocals on a good recording will float just above the instruments. The base is rich and full and will go very low without a lot of bloating. The base may not be big enough to satisfy a base head, however and analytical listen would consider it...

These sound similar to the M50 however the sound stage is wider. Compared to the M50;s the highs and lows seem to be a little more rolled off. The great sound stage makes these are great for gaming. The mids are same qty as  M50 but more spacious.