A change in efficiency to the final sound

I have a p/p tube amp running a pair of 6Ca7's for about 30 watts per channel .
I have read here that p/p tube amps sound their best when they have to work a bit harder , as opposed to a SET amp that sounds best near idle .
My present speakers are claimed to be 92 db. eff.
If this amp is driving a pair of speakers rated at 85 db. efficiency , should it sound a bit better due to working a little harder or closer to its optimum level ?
Conversely , would the same amp sound a bit worse driving a more efficient speaker of 99 db. due to it working less hard or further away from its optimum level ?


Thank you