i know burning in helps, which it ‘has’ definitely over a few hours playing, but how long should I give them before (perhaps returning them under their generous 30 rule?)Send them back, others here will have you burning them in🤦♂️ changing directions (yeah right when the mains changes direction 60 x a sec)🤦♂️ until the cows come home, when the send back period expires, then you’ve done your $$$
Just put the money into a component upgrade instead.
All you need to know about fuses that change sound is:
.https://forum.audiogon.com/posts/1860594?highlight=fuse%2Baging
Also snailspeed go the the "Misc Audio" forum for snake oil voodoo fuse info
Cheers George