Hi again Rush1:
Well, amplifiers! I can only offer my own experience. Since I've owned my Duntech Princess (a sibling to your SC-IV) I owned a variety of amps, tube and SS, rated from 100 to 400 wpc into 8 ohms. My Princesses are 4 ohms so they draw more and are rated at 90 dB. Don't be fooled. The impendance curve drops below 3 ohms at two different frequencies and that crossover we've been talking about is a very complex first order unit. The other factor, which may add to my situation, is that my woofers are Dynaudio. All this adds up to a demand for clean power. About 18 months ago I bought a pair of Halo JC-1 mono amps rated at 800 wpc into 4 ohms. My speakers have never sounded so good. Detail without harshness, extension, depth, musicality, warmth without becoming syrupy --- you can enjoy them for hours without listening fatigue.
A friend brought over a PP 300B amp, thinking with 90 dB they might work. Those amps fell on their face attempting to drive the Princesses. So I cannot image any SET will provide satisfactory performance, let along being optimal. Sorry, Dunlavy's designs need quality watts and a goodly number of them.
PS - The Miller Sound I recommended does repair work. I was not aware they might sell drivers. So I hope your speaking with Bill LeGall.