Harbeth 40.2 or Vandersteen Quatro CT

Since the Quatros have built-in amps in each speaker for the subwoofers, your amps will only be driving the mids and tweeters (using the hi-pass filters). Those Pass monoblocks may be overkill? If you love the Quatros, the matching Vandersteen monoblocks are said to be a wonderful matchhttps://www.vandersteen.com/products/m5-hpa
The two speakers are apples and oranges. Quatros are a true full-range floor-stander.with amazing bass. A dear friend has them and they are amazing.

karmapolice

Tomic has the Treo CTs I know, which I have heard and love as I do the Quatros. If you are satisfied with the bass response on the Harbeths (frequency response: 35Hz–20kHz ±3dB ), would you be seeking a lower range with the Quatro CT (frequency Response 24Hz – 40kHz +/- 2dB )? The bass of the Quatros is amazing for sure.

The Treo CT has a frequency response of 36Hz – 40kHz +/- 3dB, per Vandersteen’s website. Very comparable to your Harbeths on the low end. I have listened to them at length, and they sound wonderful. I could live without the lower bass extension I think, but I don’t know what types of music you prefer. I am not sure which would be best for a smaller room, in other words if the Quatro’s bass would overload the room without acoustic treatments. It does have an adjustable crossover which may alleviate that. From their website: "High-pass filtering allows the main amplifier to perform better, unburdened of reproducing deep bass, and is also the only way to ensure flat frequency response at the crossover to the powered subwoofer. Passive speaker designs always require placement compromises between the areas in the room where the imaging is typically best (farther out in the room) and where the bass is best (closer to the walls for boundary reinforcement). In Vandersteen’s powered-bass speakers the speaker can be placed out in the room where it images best, while the 11-band EQ ensures powerful but perfectly tailored in-room bass performance. The best of all things."

Both of these Vandy models do well placed fairly close to the wall, which is why I want the Treos (can’t afford the Quatros). I have the 2CE Sig III now.

The advantage to the Treo is the lower cost, and the fact that your amp runs them at full range (you have plenty of power for that) and you don’t run the high pass filters as you would with Quatros. You could later add subwoofers with the Treos if you want more bass, which is what the rep at the dealer I shop at did.

There is no wrong answer! And as Tomic said, the Harbeth 40.2 (which I have heard) are wonderful speakers too.

Oh, to have to decide!

tomstruck

Absolute Sound has a review of the Kento in the new edition, just arrived last night. I haven't read it yet, but the teaser says it's amazing. From what I have heard listening to the Quatro CT and Treo CT, I would be very happy with either (esp the Quatro!).