I believe you can shut the phono section off, so, in effect, you will have 4 spare tubes. FWIW, I swapped the factory tubes on my C220 for Mullards, current production. They are quieter and slightly warmer sounding than the stock tubes.
Tube rolling on MacIntosh C2300
I want to try out some new tubes on my C2300 preamp. I only have one source, a DAC/Streamer and do not have a turntable. The preamp has 6 tubes of which 4 are for phono (2 MM and 2MC). Should I change the phono tubes as well or since I am not using the phono stage, it will make no difference?