I had a pair of HD 650s that I was using until just recently. The Explorer2 drives them just fine. Being open-back you won't be able to crank them in the office anyway despite assurances from your neighbor. They are very neutral with accurate bass in terms of attack and depth. I liked mine but found them to be uncomfortable over long periods of time. They were tight on my head.

Also, they are not too comfortable if you wear glasses.

Last edited by Dollar2; 2017-02-02 18:46. Reason: added glasses comment
Regards,
Bill

Theater: 861v8+ID41, 218, (2) DSP8KSEs, DSP7200VCSE, (2) DSP5200s, Marantz UD9004, (2) JL Audio F113s, Roon
Whole House: 218s, DSP520s, DSP 320s, Roon
Office: 218, DSP3200s, Roon