My recent experiences : I got my 15" HPD's into some new 'narrow' style Birch Ply GRF cabs. Ultimately they will have Reds in them.
First I used my trusty beast of a Class A 6SN7 / KT88 PP of circa 20W (uses silicon power reg and 25w tail resistors and a 12Kg mains transformer & consumes about 300W of mains at 239V I have here).
All good... Drives the Tannoys nicely and sweetens the horn upper mid/tweeter.
Then I tried a £70 Topping TP22 rated at 25W into 8ohm.
This is the largest D-class I currently have - I say that as I have a 50w into 8ohm under investigation.
The TP22 does get hold of the bass quite nicely actually.
Much better than the tiny T-amps that just run out of puff on Tannoys.
Bit harsher on the mids and treble over the Valve amp but still pretty good considering the price and running cost consideration. On some music types I found it quite acceptable.
Allowances have to be made cos' I was using the Reds crossover on the HPDs which is not ideal I guess.
Will see how they sound with Reds X/O and Reds drivers...
Demo'd some GRF cabs with the Reds in and on the Reds crossovers they sounded great.
I used a Icon Audio 5W SET (EL84) amp and in my large lounge diner space they certainly filled the room with sound.
Plenty of power and bass believe it or not.
They will be driven ultimately by a 8W SET so just 5W doing all that was heartening.
Updating my experience with my Almarro 318B.
I had it modified to include a variable negative feedback switch.
It seems the standard 318B has too much negative feedback for the Tannoys.
It sounds really good now with just a hint of feedback or zero feedback.
I looked into the Almarro brand as a potential purchase if I was to buy new. Read good reviews about their products. Good to hear you are enjoying yours.
I am still hoping to find a good ST20 for reasonable money but recent fleabay prices has somewhat made it unattractive to go down the vintage route when international collectors are bidding silly money for them.