Expectation bias can be easily eliminated by careful testing and listening. It’s not really that difficult.And it's obvious that you can't do either, especially when you state they are directional.
All your maybe hearing is an old fuse (pictured) that seen too many turn on cycles, verses a new fuse, you may as well just get a new $2 fuse instead of the $130 boutique one.
https://i.stack.imgur.com/0uqWX.jpg
Cheers George