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.
i'm using a bendix 6106 rectifier, electro-harmonix 6SN7, and sovtek KT66. check this thread here for more tube options:

The reference was perfect! I've ordered a couple of Sylvania 6SN7s (late 50s or early 60s) and two Tung-sol 5881s from Vintage Tube Services.

Can't wait to hear what difference they make.

Thanks again,