In addition to what genjamon has noted, I'll add that this amp does it's best work into a speaker with a fairly benign impedance curve. In other words, genjamon's Tekton's are a great fit. When I matched the the STA200 up with the 4 ohm Spatial M2 Turbo's, not a good match. After about an hour, the amp got fairly warm and the presentation became somewhat ragged. So in summary, I'd say speaker matching is every bit as critical as pre-amp matching. In the end, I shipped it back to Audio Advisor within the 30 day audition period.