Not on board with all C-note recommendations.
They are not that great. I would not build them if you are looking for speaker that competes with the best commercial offerings in the $500-$800 range.
The C-notes are not comparative with any of them. Compare them with the better offerings in the $200-300 retail class and then maybe but I found in my listening they are still beat out there. Especially if you factor sale prices.
You are going to be spending time building them, which I think is very fun. I love DIY, that said the best commercial systems have nailed the $200-$1k range.
To beat a pair of Revel M16's ($700pr on sale right now)will require some really well designed DIY gear.
That said I'd consider building the HiVi kit. Based on my experience with DIY it looks very nice and does likely fit in with more expensive commercial speakers. I have never heard them though.
The CSS kit uses a well respected Wavecore OEM'd woofer that has pretty deep bass ability. If using subs this won't matter but on their own they might have pretty great bass. They match this with a 22mm tweeter not in a waveguide. This seems like a tall order. I wouldn't buy these unless Klipple tested or at least home Spinorama'd. I'd have a hard believing that beyond deep bass, many others would not exceed the CSS speaker.
Between the 2, I am just guessing the HiVi is the better value and perhaps the better speaker. CSS is not an OEM and HiVi is, so the price difference is basically that. If CSS sold the 3.1 it would be $700.
(In any case again skip the C-notes.)
If I was trying something out, I would build the SB acoustics BROMO over the CSS. $470pr
SB Acoustics Bromo 2-Way Speaker Kit - Pair
www.madisoundspeakerstore.com
Or maybe connect with this members work found here and build something with a contemporary waveguide.
After seeing the success of Directiva, But knowing the price, I wanted a nice small pair of passive bookshelf speakers for use in the second living room. I didn't need massive SPLs (if you need more SPLs the Directiva is much better - however that build is DSP XO + Multi Channel amplified). The...
www.audiosciencereview.com
If I was someone looking at the C-notes and needed small speakers or had subs and had a small budget(and cabinet making skills) I would build these for $250pr.
ZA5.2 TM 2-Way from the Zaph|Audio ZA5 FamilyPrice shown is for a PAIR This is the 2-Way offering from the ZA5 family of kits. You can build this kit in either a ported or sealed box design. This design also has a crossover variation for In-Wall use which you can select from the drop down menu...
www.madisoundspeakerstore.com
Rabbit hole
Troels's DIY Speaker site is fun
Heissman Audio DIY
Lautsprecher Bausätze und Baupläne. Bester Klang aus selbstgebauten Lautsprechern. Magazin zum Thema Lautsprecherbau und DIY-Hifi.
heissmann-acoustics.de
Meniscus Audio DIY kits
I built these with my GF. Wanted something in kit form for her. They sound great, though they use a smallish woofer and could use sub bass reinforcement. Beautiful Walnut front baffle and some complexity getting the whole thing together. More expensive but included just for fun and as another example of a quality DIY kit.
Speaker Series No.1159 is a medium sized stand mount featuring a horn loaded dome tweeter using the ES horn flare geometry. The 40mm thick solid hardwood baffle has the horn itself machined into the baffle as one piece. This results in a clean contemporary look while allowing the horn geometry...
josephcrowe.com
I believe a kit for this was/is in the works. Maybe a long time now though as this site is based in Russia. State of the art though and prolly expensive, just included here for fun.
Идея проекта и выбор динамиков Идея проекта PuriBliss-BeWg возникла в октябре 2019 года сразу после тестирования мной новейших басовиков PTT6.5W04-01A от датской компании Purifi и бериллиевых твитеров T25B-6 немецкой компании BlieSMa. Оба динамика показали наилучшие объективно измеряемые...
hificompass.com
Anyway.
I'd buy both the dbr62 and Revel M16 with good return policies or at prices easy to recoup on if reselling. Spend a few weeks with both at the same time. Keep the one you prefer. This is an important step. As an example I prefer the M16 over the dbr62 by a wide margin, but you could be the opposite. They do not sound the same.
Then using that keeper as a reference, start getting into DIY with something to validate what you are hearing.