I would say you are pushing it to drive the virgo's with 15 watts. It might work. I have run mine with a 45w el-34 amp and thought it had plenty of strength, but none of the bass that you are paying for with a virgo.
They definitely sound better with more power. I recently put some high current 220 watt tube monos on mine, in place of my normal 100 watt stereo amp, and found the soundstage to be MUCH larger and improved. It is remarkable how much the bass improves with additional power. I ran a 375watt/4ohm solid state on them for a time, and they sounded like I had added a subwoofer.
Let us know what you find !
They definitely sound better with more power. I recently put some high current 220 watt tube monos on mine, in place of my normal 100 watt stereo amp, and found the soundstage to be MUCH larger and improved. It is remarkable how much the bass improves with additional power. I ran a 375watt/4ohm solid state on them for a time, and they sounded like I had added a subwoofer.
Let us know what you find !