What component to upgrade next?


Looking to upgrade a major component. Budget ~5k. 
Here’s my current set up. Listen to 50/50 vinyl/digital.

Parasound P5
Parasouund A21
Revel F208s + Gaia 2s
Project DC Carbon + Isoacoustics Delos
Chord Cutest DAC
Bluesound node 2i
Nordost Blue Heaven interconnects for everything
Nordost Hemidal power cables
Isotek power conditioner

Open to ideas for minor upgrades as well. 

Thanks!
etherscreen
Looking to improve the overall quality of the listening experience - soundstage, sense of space, etc.

You would be shocked at the degree to which you can improve these things for $5k with:Synergistic Orange fuses, HFT, ECT, and PHT. You could do full room and system and have plenty left over for- 

Nobsound springs- turntable, speakers, amp.
Cable Elevators.

And that's just the stuff I'm allowed to talk about on-line.

what tube preamps would mate well with the Revel F208s and A21?
Unfortunately, I believe the A21 has a 33k input impedance. Most tube pre’s would have a rolled off low end driving that impedance.
You would need to look closely at the coupling caps the pre under consideration is built with.
Though the pre's output impedance will play a role, you would probably want at least 2uf minimum, that would get you to about 25hz.