Is there a glass ceiling for cable technology??

In a word, no.

Having said that, I've gotten the best results I've had with some plain old 16 gauge .9999 soft annealed silver wire with an 8 gauge teflon tube that's so big it makes air the primary dielectric. No connectors, just bare wire.

All the best,
Nonoise

Audioquest ICs - polyethylene or polyethylene foam, or polyethylene foam in oversized tubes, Teflon, Teflon foam, Teflon foam in oversized tubes. Metal can be very pure but standard oxygen free copper has still thousands of crystals per foot(impurities reside between crystals) while the best metals have one crystal being made in hot forms that allow to cool metal slowly preventing crystalization (Ohno Continuous Cast).

My interconnects are 0.5m XLR Acoustic Zen Absolute (silver in oversized foam Teflon). While typical cable capacitance is about 30pF/ft - Absolute is 6.1pF/ft

How does it sound? It is more refined than previous 10x cheaper 0.5m XLR AQ King Cobra. Everything is a little bit better. Sound is slightly smoother, faster, cleaner with the same neutral balance. Is it worth paying 10x more? Perhaps not (for my system), but I got very good deal (and it is going to stay forever). It is for me point of diminishing returns. Even with better system and better room my ears are still the same. This point of diminishing returns is different for different people. Some are satisfied with lamp cord and it is great - saves a lot of money.

Even determining the ceiling at present in any quantitative versus qualitative way with wires may be an impossible task.

Each will have their own opinions based on what they hear. That's about it. I do not foresee any large government funded research projects in the foreseeable future that might put these kind of audio twilight zone questions to rest.

My opinion is that if teh system is good and working to user expectations overall otherwise, finding wires that fit in properly should not be that hard with a little trial and error along the way. Need not cost a fortune, unless teh final frontier of wire technology is something that truly peaks ones interest.

Nonnoise, can you link to the source of the wire you describe? I would like to consider it. Tnx

Jim-

one would think that there exists a glass ceiling for all things cables/cords.

Remember, there is a ton of over-priced junk being produced by boutique operations. The better cables/cords are not mass-produced (Kimber, Cardas, Transparent...etc.).

The best cables/cords are being made by hand and to-order.
Also, there is a strong metallurgy component to be factored in as well. Examples of this practice are the newest Audience, Stage III Concepts and Silent Source offerings.

Disclaimer: I am a cable/cord guy at heart, yes, they do make a difference!