Disagree with the idea of ditching the Pass power amp for ARC when OP is looking for warmer. I've owned a number of Pass amps, most recently XA25, and currently have a Ref 75 SE. ARC can be eye opening and very impressive, but doesn't have the warmth, richness, and density of Pass. They are just different sounding.
As far as preamps, something 6SN7-based like the Cary might the ticket. I like Von Gaylord as they definitely have the midrange magic, but are minimalist in terms of features if that's important to you. I also had the CJ CT5 with a Pass XA30.5, which was a great match. Warm, but pretty open sounding too.
Good luck!