I've only had one pair of loudspeakers that changed dramatically after a short break-in. Everything needs some burning in but mechanical drivers used in loudspeakers get to one-million cycles pretty quick. Hook them up and enjoy.
Speaker Break-in
A search brings up lots of good, past discussion on this subject, so I have a good idea how to go about this. I have new speakers coming next, the manufacturer says this: "You shouldn't need a break in period the surrounds are already very compliant," In turn, the dealer says this: "Yes, just about every speaker needs break-in, less so than other models as they don’t feature internal amplification, but they’ll still benefit from a couple hundred hours of break in"
Speakers are Legacy Signature Se...Any thoughts?