I've owned Raidho C1 and D1 and now have the D2. The D1s like power. In most cases, fast powerful (at least 100 watts, preferably 200 watts) solid state amps are preferred, but there are some rare high power tube amps that do work very well with these speakers as well. According to one dealer I trust, he doesn't like warm sounding solid state amps and tube amps with the Raidhos, as the speakers already have a slightly warm sound in the lower midrange and upper bass. So tube amps like VAC or most ARC, which IME don't have very good bass contro, may not work well. However, for some reason switching amps from ARC and NAD seem to do very well according to the dealer. I've used high powered tube amp with these and like it very much, but my tube amp isn't particularly warm like McIntosh for example. However, they do require a tube amp that can control the woofer with authority. Raidho seems to like Solution and Constellation amps, but I think those amps are way overpriced. I've heard the D1s with Rowland amps, which are very smooth sounding with D1s, but IMO lacks some liveliness. I would agree the 75 watt Coincident amps would not have enough power for the D1s.
