Harbeth 40.3's. Should I buy them?

@avanti1960

... is correct - the Harbeth 30 and 40 series require a good SS amp to bring out all their capabilities and sound their best - just as Harbeth "suggests" - they typically show them driven by Hegel SS amps. As I noted before, mine didn’t sound great, until I got the H590 to drive them properly. Now they do!

Though, I like their sound with "all things acoustic" - I don’t listen to rock much. As I noted, with the "all things acoustic" they are superb and sound very much like Quad ESL 57’s - which are the best there is with that type of sound (when set up and driven properly).

Though... as I noted previously... if... I had the right room for them (and could manage them physically)... I would have the Legacy Audio Aeris, or Focus SE / XD’s - which do it all as well as it can be done - Superb! They may not sound as much like the ESL 57’s with the 57’s "rich, liquid sound"... but... the Legacy’s are the next best thing for a wide range of music, bass, percussion and dynamics... when you want that!

I’d recommend big ProAc’s D48R sound amazing big and fast and visually not weird or ugly. You have the perfect amp for them ProAc’s love tubes! I’ve owned lots of speakers and I’ve always come back to ProAc’s! The D48R is the top of the response line. There’s also the K series much more $$ but better. 
 

I also like the Dynaudio. I think that the Dynaudio have the best Soft Dome tweeters. If I had the cash the Dynaudio Confidence 30 would be a real contender. But I really love the ProAc Ribbon tweeter. 
 

The Vandersteen Quattro Wood CT are a Fabulous speaker. A must Listen!

I think the Magico’s are also Wonderful even the smaller A series are awesome the A3 . Get a listen!!

HTH

@bassdude ...As I noted before, mine didn’t sound great, until I got the H590 to drive them properly. Now they do!

+1 what @avanti1960 said too.

Harbeth, Spatial, Legacy, Quad 57s - all can sound good when paired up with robust amplification combined with good room setup. Having tried building pseudo replica ProAc floor standers years ago, how they can pair up so well [as @axeis1] suggested, with some lower power tube amps - is still quite interesting to me.

I am always surprised when folks say that Harbeth speakers don't rock. I have 30.1s driven by a Luxman integrated. They rock. 100 watts of Luxman power drive the 30.1s extremely well, and when I pull out some classic rock (The Who, Rod Stewart/Yes) they sound great. They do not have ear piercing treble shrillness, but they sound great, and I have worked hard to minimize tremble hardness.  Also using the Luxman amp allowed me to stop using a sealed sub in the system. I get very nice bass in my room without going through the painful process of matching and tuning a sub to the room and speakers. The sound is more cohesive without a sub (for me, in my room, with my system and ears). Good luck on the search. There are a ton of nice speakers out there.

having been a lifelong fan and owner of numerous big spendors, harbeths and proacs over the years, i would add that having the right amplification for each is (obviously) important in extracting the best performance from each, and also knowing how each has/had been developed is useful

harbeths are less efficient, proacs typically the most efficient (the outlier response d38 an exception), and usually use multiple smaller woofers in a d'appolito configuration, spendors somewhere in the middle ... stewart tyler has historically optimized/voiced his upper proacs with medium power arc 6550c tube amps - so if you hook up solid state to proacs there is a chance they can sound a little bright

it is well known that modern harbeths have been typically developed and run at shows using hegel solid state (h360/390) and quad before that

spendors (terry miles and derek hughes earlier) use solid state mostly (quad 66 and naim power amps) in their testing and voicing.... that said, spendor classic 100’s and their predecessor s/100/sp100/r2 models are quite tube amp friendly with impedance well above 6 ohms through the range and around 89-90 dbwm efficiency