I am driving my X5 speakers with 45 tube amps (less than 2 watts) and the sound is stunning. I play some rock very loud and have yet to hear any indications of needing more power. Some write about their speakers really coming alive when they use a higher power amp, but I see no need for this. In addition to the powered subs in the speakers, I use a pair of GR Research dual 12" servo OB subs so my 45 amps only power the top 2 drivers. I have placed Bybee products on the top 2 drivers, but these seem to have no effect on sensitivity. My room is 20 X 20 X8. I play almost no orchestral music. I imagine if I could have a higher power amp that sounded as good as these I might prefer it, but as it is I am very happy with the sound now. What other low power amps are you using (if any) and are you happy like me with the sound, or do you want to use more power?