Without knowing anything about your musical tastes and how loud you listen ... you would be going from floor standers to stand mounts with the Harbeths. Do you have any concerns that your cat (s) will look to topple the new speakers? That would be my first concern. I use my stand mounts (Omega CAMs) on top of bookshelves for that reason. The speakers sound fine, but some of the audiophile niceties get lost.
Second concern would be the speakers' efficiency. With the Leben's output @ 15 wpc, you will want efficient speakers. That may disqualify the Harbeths.
I don't know the other two speakers. I am presently running both Zu Audio and Omega CAMs with my systems.
I like the look and what I have read about the Nines. I might obsess that Pattie Cat and Tony would find the side mounted woofer a little too tempting and interesting, but I would do the trip to audition them.
Apologies for the feline approach to speaker selection, but it would be a big part of the process for me.
I’ve owned the 7ES3 and I doubt a 15 watt amp would be a good fit. The 3 grand is overpriced for that speaker. $2500 or less would be more of a ballpark price for them in the standard cherry finish. BTW, you will also need stands with them!
I owned a Leben CS600 and demo’d it with Harbeth and didn’t think it was a good match. At 91db, the Devore or Reference 3A are on the edge of acceptable sensitivity depending on your room size, listening volume and distance of your seat from the speakers.
You’d be wise to consider something around 95db or above. Have you looked at Tekton Perfect SET or Perfect SET 2-10?
Chris, @lalitk offers a very wise and doable suggestion. I’m skeptical about the Harbeth driven by the 15 watt Leben however you have the fortunate opportunity to take your amplifier and listen for yourself.
No matter how well intentioned or thoughtful some of the responses you’ll receive here, the ability to actually hear, the Leben with your list of speakers is the superior option. Charles
I’m using a 20-watt Raven Audio Blackhawk with the Reference 3A de Capo i speakers and it has considerably more than power than I need for anything in the wide range of music I listen to in a medium size living room.
I owned the DeVore Super 8 speakers and absolutely loved them but was driving them with a considerably more powerful amp.
Should you choose to look outside your aforementioned choices, I highly recommend Tannoy Stirling (used) if you can find them. I have paired Tannoy’s Prestige Series speakers with Leben and Accuphase and they are absolute joy (non-fatigue sound) for long listening sessions.
Based on your question, lalitk has the perfect advice. You're in the unique position of being within reasonable driving distance of all 3 speakers that interest you. Pack up that amp and take a few road trips.
I’m driving the Tekton 2-10 Perfect Set with a 20 watt Schiit Aegir. $2k delivered for the Tekton’s. You don’t have to drive anywhere. 60 day home trial. Play louder than I would ever want, even for rocking out.
You’re really missing out if you don’t give them a try.
Strongly agree with the pack up amp and audition recommendation. If the list gets too big and needs some trimming, I would suggest sending it to Leben and asking if any options are particularly good matches in their experience. They've got more relevant experience than anyone in here.