I bought the ES100 for it's multi uses in my listening routine: as a USB headphone amp that provides the extra juice for my Beyerdynamic Custom Studio 80 Ohm at my office, making some cheap earphones sounds way better while cutting grass, or adding high quality bluetooth streaming to my old...

https://www.amazon.com/gp/product/B00MT56WLU/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1   Little pricey than some others, but good reviews and it was an impulse buy.  Build quality is good although the first time inserting into the H6 required just a little extra to the right connection...

Just got new cable for my BeoPlay H6 2nd Generation and all I have to say is B&O is doing a great disservice to these headphones with the stock cable.  Holy crap does the new cable improve the sound quality!  I also think the volume better but the clarity is definitely there.