Tube Preamp for Rega Osiris

Anyone have any experience running a tube preamp with a Rega Osiris as the power amp?  Looking for any advice/ideas on bringing tubes into my all Rega solid state system.  

Gear: Rega Osiris, Isis, Aura, P10, Harbeth C7ES3
I had the REGA R9 floorstanders (predecessor model to the RS10s) I moved to standmounts when I moved by 2-channel sysytem out of my mancave and into a smaller FR and more intimate listening arena. The mancave is strictly a 7.1 home theatre arena now.

IMO its your silver speaker cables (inherently bright …) paired with the high-resolution HARBETH’s that are the easy culprit to identify in your quest to get a warmer presentation. The CARDAS CLEAR XLRs removed a lot of that inherent silver cable edge and brightness in all silvers including the NORDOSTS. The synergistic move to CARDAS speaker cables flows lockstep

The ISIS VALVE cdp/DAC is a worthy large step in a tube proxy “warmer” overall performance, but still retain all the finesse, dynamics and the slam of every ISIS. A great partner with HARBETHs,