I have a Vali 2 and ModiMultibit, paired with the HD650's. I also have the HE-400I's and X2's, and would use the HD650's whenever I have proper amping, and X2's when I don't. From what I have heard, the DAC/AMP combination I have been using works great with most Sennheiser headphones, and I was curious if the HD800's would be a worthy upgrade as a daily driver. I would also be happy buying a few more pairs, like the HD600's and M1060's. Any recommendations would be great.