Cary 308T volume control question

I'm new to the cd player with volume control world, and I have a question as far as system use. Should I turn the volume all the way up on the cd player and control volume through my preamp (shallco attenuator)? Will this limit the life of the tubes? Or should the volume be turned down on the cdp to about half? I'm confused as to which way is best from an operational and system life point.

Thanks in advance,

I was told by Kevin at Upscale Audio and Guy Hamel at Placette Audio that it should be turned up all the way to minimize its effect on the sound. I do not know if this alters the tube life.