How make my Ayre system "warmer"?

You might keep in mind that tubes are not the only components in those pieces of equipment, and that designers of SS equipment have historically taken vastly more drastic steps to minimize distortion figures(ie: typically 40db of negative feedback), usually to the detriment of actual sound quality. Tubes are innately very linear(into RF frequencies), but unfortunately, provide relatively little gain/transconductance(low output current) and high plate resistance, hence the need for matching transformers. A great deal of the distortion inherent in tube amp design results from the use of transformer output coupling, not the tube itself.

Hi Tvad- Like most subjective evaluations with regard to this hobby: One person's candy will be another's poison. My first Mullards(CV 4004) were tried in a CAL Alpha DAC, when I had a much less resolving system than now. Their warmth was much more than I could accept even then, and they were quickly replaced with Tele's(ECC83's). No problem with soundstage, imaging, etc., but the coloration was simply not natural. I agree with your ranking, RE coloration levels: Brimar, Mullard and Amperex(the "pinched waist" I could probably live with). To me the Siemens and Telefunkens(whatever family of nine pin miniature) are the most transparent, extended and uncolored(natural) out there. Let me narrow that last statement to the pre-1968 tubes manufactured for the German Telephone Services, and branded as "Specially Selected"). One nice thing about Mullards is that, once tried, if not appreciated: they are easy to sell. I do love their voltage rectifiers though.

To cut long story short, try Kubala-Sosna Emotion powercords, and when your budget allows it add IC's na SC.
You will not lose any resolution and balance will lean more to the bass.

I've got six NOS(pre- 1968) CCa's in my CDP(BAT VK-D5) and enjoy their presentation very much. Like you said, "It's also the gear into which the tubes are placed." My goal has always been to recreate(as much as possible) what I hear and feel in the live venues I visit/work a couple times, every week. It's been my experience that most people blame excellent components for shortcomings elsewhere in their audio chain. Again- Everyone has their own tastes also(I believe I mentioned, "subjective evaluations"). BTW- What was the manufacturing date on those CCa's you had? The ones made after '67 could singe your ear hairs with their stridency.