Any experience with Thrax as a preamp?

I am considering replacing my beloved VAC Phi Beta preamp. Possible contenders include the Thrax dionycious, Constellation Audio entry level, Jeff Rowland Corus, or upgrading the VAC for an used Renaisance iia. I will have a chance to audition the Thrax, but several of the online reviews have not been kind to is quirky volume pot, and comment on lack of full, robust sound stage and warmth. I know that Thrax is still highly regarded, but have not seen any specific folks on the forums with Thrax who provided insight into its sonic character strenghts, and flaws. I am looking for a pre with a pair of outputs in rca, as I use one set to output into my powered JL Fathom sub, other to amp input. Helpful comments would be welcome, and appreciated.
Happy New Years!