Moving away from inefficient/low impedance speaker in order to move to a Tube Amp

I have no need for inefficient amps that double as room heaters. Try the fabulous AGD amps, they look like tubes, they sound like tubes, they drive any speaker. They consume less energy, save you money, tubes don’t wear out. They even glow orange! To me, the future.

I think it is a matter of finding the right speaker and then matching them with the proper amplification.  Even if the the speakers are supposedly not efficient enough to work well with lower-powered amps, I personally find that, in most instances they can be made to work with modestly powered tube amps.  I find that most people grossly over estimate the amount of power they need or try to achieve rock concert volume level even though the speakers and the room itself are ill-equipped for such practices.  Every choice is a set of compromises and I personally choose to go with very high quality at modest listening levels, and every improvement I make tends to make the sound enjoyable at lower, not higher, volume levels.

If you like the Harbeth speakers you have, I don't see how you can save money by getting another speaker of higher efficiency and then looking for a lower powered amp.  The really good sounding low powered amps are NOT cheaper just because they deliver lower power.  High power these days is cheap to achieve, quality at all levels of power is not. 

My local Harbeth dealer sells only tube amplifiers, and most of them, including the best sounding ones, are low powered.  The only Harbeth model that seems to benefit from higher power is the 40.2, and even they sounded their best with particularly good lower-powered amps (but played at decent, but not extremely loud levels).  

It has been said over and over on hundreds of posts. It is the old horse power vs torque argument in engines. Watts per channel is only a small factor in the overall power of an amp. You can buy an amp with 500 wats per channel that has no power and you can buy an amp with 5 watts per channel that has tons of power. Do the research and reach out to the companies to break down the amps total package and specs. In todays world you might even be able to contact the designer and ask them to define your solution.

I used Primaluna 36 watts to drive 88bd Salk Songtowers with great ease.Then traded up to 70watt Primaluna Evo 400 and found it didn't really make much difference in the ability to drive the Salks but sounded better.

Then I bought 93bd Tannoy Turnberry GR and that made a big difference in detail. All these subtleties came through.Will never again buy a speaker of even average efficiency.

Thanks...the system will be a second floor bedroom, that is around 19 X 15, with standard 8 ft ceilings.

In a bedroom system your speakers will be fine if you have the space unless you really plan to blast. I would think an amp with 15-20 watts would be plenty. You might want to add a sub just to handle 50Hz and down.

If you get something like the ZU Omens I would expect that in a bedroom you could do well with an amp of only 5 watts per channel.

Bedrooms for the most part simply don't need to play all that loud.