Back in the 80s and early 90s I enjoyed a set of Mission loudspeakers that came with protection fuses mounted on their rear panel. They were my first store-bought speakers, as I had previously only made my own speakers. I bought them because they were smaller stand mounted speakers than I could build myself with similar bass and other qualities I desired - back when I was living in a small apartment. Basically, Mission could accomplish the performance that I could with a two-way in a smaller cabinet than I could, and being newly married having smaller speakers would be better in our small living room.
Anyway, I noticed that the speaker fuses were very low current rating fuses, and also I knew the power amplifier I had built had a decent protection circuit that would not put DC across the speaker, so I made myself a set of "bypass fuses". I put a 1/4 inch wide strip of copper foil tape across the glass/ceramic part of a pair of fuses and then soldered the copper foil tape to the tinned fuse end caps.
So with one pair of regular fuses and one pair of "bypass fuses", of unknown but vastly higher current rating, I experimented with switching fuses and listening to music. I did this first myself, and then thinking I heard a difference tried running this test with several friends and also my wife listening. Only I knew which fuses were which, and which were installed at any point in time. I was careful to not give any cues as to which fuse I was using and I randomly swapped the fuses numerous times with each listener. Every person could identify that one of the sets of fuses had more bass impact than the other, and that was the pair of "bypass fuses". In the time I owned those speakers there was never a failure of any kind.
Finally, I know that Eminence sells pre-made crossovers with a tweeter protection lamp (light bulb) on their board. I have never used them but thought it was interesting. I believe they were pro-sound crossovers.