KEF iQ5se Amplifier matching

Hi, I already own Kef iQ5se speakers which are currently paired with a Pioneer A400. I am looking to upgrade to a higher end integrated amplifier.I have had conflicting information about amps that will pair well with these speakers. I have asked for suggestions from a few HiFi shops.
-Originally i was interested in the 'Unison Research-Simply Italy' but told it's not powerful enough and only be suitable for quiet to moderate volume levels.
-Recommended the 'Icon Audio Stereo 40 MkIV' which I was feeling hopeful about. But then...
-Another shop said "Tube amps in general will not sound good with these speakers". Said to look at the 'Naim XS3'.
-Spoke to gentleman from another highly rated shop and he said that Naim amps will sound terrible with these speakers...far to much top end. Perhaps he was thinking of a different model?

I really am confused and would like some further help with this.
Budget is £1000-£2500. Happy with Used, Ex Dem or new. Tubes or Solid state...Whatever will sound best with these speakers.

I am unable to visit shops to test so am purely going by reviews and recommendations.
Thank you...It really is appreciated.