I have the SLP-05 without the upgrade, will do it when I am going to be away so I won’t miss it. Super preamp but your concern on gain is valid. I installed rockwell attenuators as suggested by others on this forum and that worked great with no noticeable sound degradation. Vinyl was fine but my digital source was too hot and I have magnepan 3.7’s which I believe are like 87 db fed by Pass X250.8.
the Cary is a fantastic unit in both looks and sound and does offer many tube sandbox play opportunities.