This question is aimed to TRUE Elec Engineers, not fuse or wire directionality believers.

Just on the surface analysis, an SSR would sound like crap, overall, in any audio application.

This is so obvious to me, that I’ve never made it past the idea of looking at the acronym of SSR, and then moved along and away from such an idea.

Ie, that the thought was discarded as thoroughly as possible, before it even began.

Like the idea of taking the tuna sandwich I might be holding and smearing it on my face, as a way of ingesting it. Silly beyond belief, not to be considered a thought whatsoever.

And that’s what I think of the idea of SSR’s in audio gear. That the thought was discarded long ago, by just about anyone in the world of audio that you can imagine.

A gentle but quick mental/internal ’no, that’s not going to work’, and then they moved on. Relay or circuit breakers is better, as the quality in sound, is better. Better than any SSR.

And all those audio designers and engineers you might want to get an opinion from, they invariably understand audio quality and that definitely includes the power cords, the fuses, and the cables -- all as being important. This is about audio quality, not some numbers squeezed out on the face of a meter and analyzed via spec sheet.

1000 kilos of raw dung will, displacement wise... fit inside my car, and the volumetric spec is there for it, but I’m not about to test that or do it.

My response is mildly over the top but honest in my analysis of SSR’s and my opinion on them in quality audio... I’m just reflecting the seeming mood of the OP itself....

I’ve never put a relay int he signal path. But Omron made nice, reliable relays electro-mechanical relays that I used in many commercial products for soft turn-in. triggered by DC - just what you need. The relay chatter issue typically comes when one uses AC to control AC with predictable, feedback-induced results. Ask me how I know.
I cant comment on SSRs.  I do believe that solid state switches are  superior to mechanical ones in low level signal paths, but they vary all over the lot.  Most power SSRs are intended for just that - power.

But where is the DC coming from? If unreliable equipment or prototypes/etc do what IO do and insert a fuse box during those periods.

Even NASA uses fuses, just like most everyone in high end audio does. Fuses have come a long way, baby. NASA started studying advanced fuse concepts twenty years ago which, ironically perhaps, is about the same time advanced audiophile fuses were introduced. Coincidence? Now, NASA might not give a hoot about sound quality but audiophiles certainly do.

- Ex NASA Range Rat