Hi Robert,
Your system looks a bit like mine. I am using the Avalon Osiris with the CAT JL2. I did have the CAt SL1 Ultimate MK2 pre but replaced it with a Chinese Ming DA 2A3 preamp that slaughtered the CAT for about one fifth the price.
I'm glad to see you are using tubes with the Avalons. I breifly (one week) tried SS with dismal results. How do you like the Magnum tuner? Have you compared it with others? Happy listening.
Bart