What solid state power amp are you using with your Harbeth Super HL5+ speakers?

I have used my Super HL5 Plus with Rogue Audio M-180 monoblocks (180 WPC) and currently ARC VSi55 integrated (50 WPC), both are tubed.  I use solid state with my Harbeth P3ESR - Simaudio 600i (125 WPC).  I agree that you don't need a ton of power. 

What exactly do you mean by "underpowered"?  If you want to have rock concert levels these may not be the right speakers for you.

@routeman21 That's about where my listening level is with my Super HL5 Plus with my 180 watt tube momoblocks.  When I really crank it, it goes to about 3' o'clock on the volume dial.  That's with my Modwright LS 100 preamp, which goes to 11!

There's nothing wrong with that, in fact, it's a good thing, because you have smaller steps between each volume step, allowing you to have more flexibility in setting the volume.  Imagine if you only had to turn the volume to the 9 o'clock position.  The difference in volume levels between each turn of the volume dial would be much greater than they are now, giving you less ability to get the volume level exactly where you want it.