Is the general consensus that the Vali will not work well with low impedance/easy to drive 'phones? I currently have Senn HD-598, Grado Sr80i, and Skullcandy Aviators. My next planned HP purchase is the Senn HD-650. I do not plan to buy much/any other cans beyond that. Would the Vali be a wise purchase for me, or should I look elsewhere? BTW, whatever I get will be paired with an Emotiva DC-1 DAC.