Questions for Rogue Cronus Magnum Owners

I recently purchased a Rogue Cronus Magnum III from a local dealer. They let me borrow their CMII to demo in my system and I fell in love with it. Their amp was lush, tubey, and romantic (as I've heard it described here on AGON). Perhaps somewhat syrupy. The new CMIII, however, sounds much more like the SS amps I've owned or tried. Kind of bright and sterile.

My questions is: How long do tube amps typically take to break in? Am I hearing 80% of what this amp will sound like after the break in period? Will it eventually warm up?

My dealer said that their CMII unit is bone stock. So I'm wondering why they sound so different.

Issue two is the hum from the phono stage. I experienced it while borrowing the CMII and it's no different on the CMIII. I went to the dealer today to troubleshoot the issue. Every TT we plugged into the Rogue's phono stage had an unnacceptable level of hum.

There is thread on another forum that complains about this same issue. Nick at Rogue has offered some good suggestions to resolve or mitigate the issue, but it still persists. Can anyone shed some light as to what the root cause may be?

Thanks,
Joe