Upgrading the preamp can often yield superior results, but I don't think that can happen for $5K. Have you considered a good power conditioner like the Audience?
$5k Upgrade
I have a clearaudio champion, zyx airy3, and k&k maxxed out phono. Thinking of upgrading and considering well tempered amadeus gta or versalex, new cartridge, or even new phono like herron vtph2. I don't necessarily think there is anything lacking, just chasing improvements.