The 2010s' 75W rating is probably a really nice match w/your Harbeths (BTW, the Exposure is a beautiful piece), and I'd say you would have to make a significant power/current jump to tell a real difference. I use old NAD pre/amp w/my Spendors, and although they are circa 1992, the combination is beyond good...balanced, smooth, and quiet. You may want to try a used NAD 272/162 combo for more current, dynamics, and low-end control. You could snag these for less than $800 on the Gon, and they may surprise you. Or how about a Parasound A21 and NAD 160 or 162? Could be another involving (and versatile) set up.