Is there a glass ceiling for cable technology??

Any cable will have a different on your equipment, so anything they put out can sound different than the cable they produced before no matter the brand. Never was a ceiling just impendence effects between 2 pieces of gear and then the wire connecting them. This why you have to try before you buy, it a crap shoot on the sound out come. Yes every year a new name to keep the product fresh and us buying them, now a new cable weekly comes out, a very money making business as a side line for many.

"There's a well-heeled sucker born every minute."
Many of these suckers are "audiophiles."

I was under the impression that the glass ceiling was reached decades ago by Monster Cable.

Of course you could just leave out the word "cable" and ask if there is a glass ceiling for audio technology in general. Since so many seem to enjoy analog and vacuum tube technologies over digital and solid state technologies, one could ask if technology in general is even moving in the right direction, let alone hit a glass ceiling.

Glass Ceilings are an interesting topic in general in this hobby.

Just how good can anything sound in given room? Its a fair question.

My suspicion is that what determines the absolute sound in home playback at this point is 98% subjective and 2% technical/objective.

Absolute sounds abound elsewhere all around us, but the biggest technical limit for home playback is probably the quality and nature of the recording.

Plus nothing stays exactly the same over time, including us and our perceptions day to day, so what sounds like the glass ceiling one day may very well not the next.

IF you are enjoying most all of your music most all of the time, then I would say you are practically in a very good place.

If you've been at it for awhile and not the case, then maybe try some digital audio streaming off even a half decent computer and some good headphones or earbuds (not the cheap stuff that comes with most devices). There is a lot less that can go wrong there as a start!