Conrad Johnson, Audio Research and Rogue Audio all are sonic matches for SF speakers.
If you are enjoying the CJ sound, demo the Classic Sixty/Sixty SE amp.
Keep me posted and have fun.
I had the 2.5s in my system on demo, and I found them to have a pretty prominent mid/upper bass bump that was tough to deal with. Of the amps I've had in my system, Bryston was one of the better ones at controlling bass, but that would have a very different overall sound than your CJ. I'd try pulling speakers out further and trying some bass traps before changing amps. Best of luck.
I had the same problem with my 2.5's. I have carpet over wood suspended floors and had my speakers in a platform that was pierced through the carpet into the wooden floor. I'm a little hard headed and ignored a friend's advice of suspending the speakers instead of anchoring them to the wooden floor. I went to Home Depot and bought two 17" square ceramic tile and layed them on the carpet and put my speakers on them. Wow, what a huge difference that made. All the energy of the speaker was being wicked into the floor and not into the room as music. Bass is deeper and much more controlled. Dynamics went through the roof. Everything was better. 1.5 years until I finally heard my speakers for the first time. So... If you have wooden floors, find a way to suspend you speakers. If you don't...
I don't know if it will better the sound or not by de-coupling from the concrete. But it will change the sound. I would buy the 6" ceramic tiles and buy some kind of foam or cut some thick carpet to put between the tile and the concrete. Just experiment and you'll find something that works. Good luck.
Dont give up on those speakers. They are very good and will respond to up front changes very well. They have a little bass hump at around 80hz, but it helps with rock.
I also had the 2.5s on a concrete slab in a good-sized room and couldn't get rid of bass hump. This bass issue has been noted by some good reviewers, and you can see it clearly in the Stereophile performance measurements...
The only ways I could think of to deal with this effectively, short of adding a sub (which is not a bad idea BTW), would again be to try bass traps or possibly some form of equalization. Best of luck.
I have a pair of Sonus Fabers Venere 2.5 and found similiar issues controlling bass roll off. I have them a thick carpet laying on a concrete slab foundation. I corrected issues by going to my local granite stone company and had them cut and polish 2-16"x16"x1.5" 20 lbs dead weight per platform plinths and placed the speakers with the spikes protectors on platform with equip spikes and found not only tightening the foundation bass but had a great improvement overall on the mid range too!
I also bi-amp with a Krell KSA 250 on low and Audio Research VT 130 se on the high and all I can say was wow now these Venere's are really performing with a huge sound stage and very black deep sound. Overall like a total different performance!
I had the opportunity to visit a dealer and hear the Prim Luna DiaLogue Premium vs the Rogue Cronus Magnum ii.
I did Prefer the Rogue over the PM. But that is just MHO.
Audiogalore that is one powerhouse setup. I don't have carpet on my floors I have a vinyl covering on the slab. where I have my spike protectors. did you use the standard spikes or special spikes? I also wish that I could move the speakers around easily are you able to do that with the granite slabs that you had made?
Yes 250 watts pure solid state Class A on Lows and 130 Watts tube power on highs. Best I've heard to date on my system. I also have a Prina Luna Dialogue Premium pre-amp driving a analog active balance crossover making a perfect bi-amp setup!
As far as the spikes I saw no good reason nor justification to the replace the stock spikes. Yes even though the granite stone plinths are dead heavy movement for tweeting the speaker placement helps tremendously!