First tube preamp recommendations (under $5k)


Right now have di20he -> terminator -> he9 -> pass x350.8 -> ATC scm7 / NS5000.
I am thinking of introducing some tubes into my chain. I like the sound I am getting but want to explore what tubes can do to the sound (slight warmth, biggest soundstage, better layering etc etc). Don’t want to go to nuts on price. If price is over $5k would consider if its really exceptional (but for sure not over $10k). Totally fine with used. Balanced would be nice but not mandatory.
So far I am thinking RP7, EVO400, bhk. Any thoughts?
smodtactical
You won't beat a Herron Audio VTSP-360 line stage. There is one out there with all recent revisions for under $5k (retail $6650).
@smodtactical There is a bit of an underground group of Pass amp owners who've found a synergy running Cary Audio SLP-98 and SLP-05 preamps fwiw.  During a brief speaker building chat, Nelson confirmed for me he has many customers doing this successfully. Another option to the great suggestions above. I still run my SLP98, works well with many amps I've tried pairing it with.   
Owned the RP7, disappointing sound, did not respond well to tube swaps. Lacked dynamics and transparency. The RH 5 sounded so much better to my ears (yes, the R "H" 5 linestage.
Currently using a Cary SLP-05, sounds spell bindingly good.
Tube rectifier and R-Core transformer.  
Some I know have the Modwrights, they love them.  
Guys thanks so much for the awesome suggestions. Lots to think about.
@avanti1960 You like the Cary better than the RH5?
@decooney gonna look hard at cary
@daveyf I can get a CAT Sl1 ref locally for about $2500.