Upgrade: will I hear it?

Been thinking about adding a true preamp and or upgrade DAC. Need advice.  Budget $2-3K. Current system is a Cambridge 851N into a Marantz AV8802a pre/pro to Bel Canto Ref 500m monoblocks to Dali Mentor 6s.  
I use the Marantz as a preamp. Before it I used an 8801. 
I listen to Qobuz and ripped files.  Jazz and Classical. I also run SACD DSD they HDMI through the Marantz and also TV sound. 

The 8802 was a big upgrade in two channel sound, and the advanced Audessey room correction really helped—in my old house. But we moved.  Listening room is now very big, speakers out from the walls and room correction not needed as much.   I’ve used the Cambridge (digital) preamp and preferred the Marantz with its room correction.  
Have my eye on Benchmark DAC3 HGC or LA4 or possibly the Bel Canto DAC 2.7. So the potential is to insert a preamp and change the DAC, or just a preamp.

I am generally very happy with the sound but it might be a tad sterile. Would welcome a tincture of warmth without losing clarity and dynamics. Do not want to fuss with tubes.
But the Cambridge DAC seems pretty darn good. Will I hear a difference. My plan is to auction two of these in home, but which two? Opinions please.