Interesting , I once read that sometimes in professional audio instead of using super , duper equipment they use fairly humdrum speakers to sound as through a normal home audio system or even worse a car
I believe it is common for recording studios to have both high quality full range speakers (main monitors) and mini monitors, and try and get the sound is good enough through the mini monitors while trying to get it really good through the main monitors. But in practice I suppose it there is a lot from studio to studio, and perhaps more so between different genres and perceived markets, and course there can be different masterings released for different markets.
Even if they didn’t, the recordings using the “hifi” tech standard of the day sound less than impressive on today’s equipment.
Led Zep’s efforts are particularly so, despite tone-deaf Jimmy Page’s “remastering” efforts, which only ended up making them sound worse.
The most interesting part imo is what the final price will be, there are probably quite a few wallet-strong Led Zeppelin fans out there…