Best way to warm up the sound

I have a MF 5.1 turntable and the 2.2 phono stage , also from MF with the stock Ortofon cartridge. I would like to warm up the sound and don't know what would be the best way to proceed .
My dealer has suggested replacing the cartridge with a Grado unit .
I have not been able to find much on phono stages and would prefer a tubed unit .
I am new to turntable mods and don't know how much change can be done with these methods . I am familiar with tube rolling in my amp and know how much change is possible there . I have an integrated amp and it does not have the ability to use a separate pre amp .
So , should I change the cartridge , possibly to a Grado ?
Or should I look for a tubed phono stage ?

Thank You