Power amp for Modwright LS100

A decent amp is just as important as rest of the components in the system.  I wouldn't skimp or settle on a cheap amp given what you're trying to put together.  

I highly recommend KWA150SE, you can buy one used at 50% or less off full retail. 

I own a pair of KWA150SE and it's a fabulous sounding amp especially when you pair it with a tube preamp. 

adg101, the tube sources I use are reputable. I'm listening right now to the Psvane's and they sound quiet today.  Some days the Black Treasures were just terrible, others not so bad.

I owned the LS 100/KWA 100se combo. Its was nice but might be a little warm for the Harbeths. I would go with something less warm than the KWA 100se or the Pass (but the .8's are not as warm as the .5's right?). If you can stretch to try the KWA 150se, it is not as warm as the 100 and might be better for the SHL 5+. Or try AR. 

@bluejeans, what did you settle on?
I have my LS100 (with Psavane tubes) paired with Hypex Ncore 400, amps, Eminent Technology LFT8b's and Vandy subs. Happy chappy!
The KWA 150se seems like a winner, but my speakers are not efficient and not sure if there'd be enough grunt (though the Ncore's are only 50w more).

I have a vintage Tannoy 15inch Red monitor speakers.  Would the Modwright Ls100 and the KWA100se be a good combination for my Tannoy?