Tubes for Chardonnay

I've read a fair number of the posts re: replacement tubes for various Supratek pres so sorry if I've missed postings that address my specific question. I'm looking for a tube combination that will bring out more of the timbre of recordings. The Chardonnay has great tone, tremendous heft and body; however, I miss some of the timbral detail of instruments. I'm using a Citation II and RWA Signature 30 as amps. My source is Cary 306/200 (sometimes through a DAC AH).

I have all stock tubes: Sovtek 5AR4, EH 6SN7EH and Sovtek 5881.

Thanks for any help you can give.
Bob