Harbeth SHL 5 amplification

I've driven my 40.1's with a 32wpc VAC 30/30 tube amp.   Not optimal, but it sounded decent.

I had both amp and speaker. They have great synergy. Try using a good Solid state preamp and use the Leben direct input, it took the combo to another level. 

Lots of owners end up with Luxman / Harbeth combos.

I make my own speakers, but I can say I really like my Luxman integrated.

As I said in my response to your previous post, you need to demo the speakers at home with your equipment.  Or at least bring your amp to the dealer.  That said, if you are looking for "power" the SHL5s will sound better, IMO with a robust amplifier. I had very good results with my Naim 250, which only had about 70 wpc, but with a heavy power supply.  Then again, you may love the sound with your Leben.  I understand that people want to gather opinions as well, but the only way to know is to demo.  If you are working with a dealer, use his services and demo the setup.  If not, just buy used and hope for the best.  Trust your ears.  

Deja Vu in Washington DC sell Harbeth and also specialize in lots of low-powered tube gear (Audio Note, custom, etc.).  Why not give them a call and see what they say will wake up the SHL5s?