Sonus Faber Venere 2.5 amplifier Recommendation

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...
https://www.stereophile.com/content/sonus-faber-venere-25-loudspeaker-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 had a pair of Sf 3.0 and liked very much the way my Mcintosh MC 152 drove them (with C50 pre amp). Any decent to good amp should be able to get the job done with ease as I did not find them hard to drive.

Depending on your budget, at $2K a Conrad Johnson MF2275 should give you what you want.

Ended up with a rogue chronus magnum ii. Breaking in now .but so far so good

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!

Enjoy music!