I personally use the HRT MSII+ with the Bottlehead Crack/Speedball along with the HD 700 and I love it. Very musical, spacious and detailed. In addition, the spikey treble has never been a big issue for me. I had the O.G. HRT MSII a while back, after I upgraded to the MSII+ I've never felt the need to upgrade my DAC at all. It's a very good combo with the entire Senn HD line, IMO.