Hello Meadowman,
I have found that even though the SCIV's are a relatively low impedence speaker, that because their impedence is very flat and not all over the map that they present a pretty easy load for amplifiers. The key is to use an amplifier with an excellent circuit design, powersupply, and outstanding transformers to give you the "quality" of watts, not necessarily the "quantity" of watts (within reason of course).
I have tried in the past a 50 watt Class A solid state design by Forte, a division of the Threshold Company. It did a fine job and was one of the better sounding solid state amps I've heard.
I am currently using a single ended triode amp using 845 Transmitting Directly Heated Triodes that gives me 37 watts rms with peaks of over 70 watts that to my ears sound simply amazing. It does not sound syrupy, or colored at all. The frequencies are not rolled off, in fact this amps response is capable of -3db from 6 Hz - 35 kHz. With this amplifier, the sound fills the air with a harmonic density that reminds you of real acoustic instruments being played. Piano, tenor sax, cellos, acoustic double bass, etc sound very, very real. I say this because I not only listen to live unamplified music several times a week, but I also am a musician. I play tenor and bass trombones as well as the cello. If the quality of the recording is there, the sound is goosebump real.
These speakers are capable of dynamics that sound natural, they throw a convincing soundstage with instruments and bodies that sound lifelike. As large as these speakers are, they are capable of disappearng. The bass that they have will reproduce an acuoustic bass with excellent pitch definition and without sounding boomy or one notish at all.
These descriptions are from listening to acoustic jazz, vocals, and classical music thru my equipment and with my ears. I am not a rocker or head banger, so I'm not sure how they will sound with rock, rap, etc. but the SCIV's can play full symphonic orchestral music very loudly with an excellent sense of dynamic scale.
I love the sound of this 845 amp on these speakers. Now if you have a huge room, you may want more power, but then I'd also rather opt for the SCV's then as well.
I have also used a custom made EL84 amp giving me a very potent 15 watts of push/pull. They sounded very nice and quite dynamic, especially the micro dynamics, but will run out of steam for the most demanding of full symphonic crescendos. They did very admirable though with simple music.
These speakers are very revealing and very transparent. If you put a hard or sterile sounding amp on them, that is how they will sound. If you put a warm, syrupy, slow lathargic amp on them, that is how they will sound. So be fore warned. They can handle a lot of power, but it is not needed if you have a quality amp and do not have a carnevous room to play them in.
I hope this helps a little.