What do $2500 speaker cables sound like?

It strongly depends on your system. Typically cabling is chosen for a level of equipment. For instance I had purchased some Transparent cables ($1,800?) about 25 years ago... they sounded terrible... because they passed through the harsh trebly signal to the very revealing ribbon speakers I owned. I ended up going with Cardas Gold Cross... probably cost $2K. Warmed the system up. Then I upgraded to much better speakers and electronics... immediately the treble was almost lost... too golden. I pulled out the old Transparent... instantly balance was perfect... clean, natural, perfect balance (like my electronics), silent background.

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Since then I upgraded to Transparent Ultra Gen 8 ~ $4,500 (my speakers are ~$32K). I don’t hear the cables.. they get out of the way. That is the way of high end cables... they don’t pick up noice from the environment... they don’t accentuate any frequency... they make for as dead a silent background as your equipment will provide. So, high end cables from highly reputable companies like Audio Quest, WireWorld, and of course Transparent. They are wonderful if you have wonderful equipment. If your equipment isn’t so wonderful then some of the many highly rated intermediate cables can be synergistic with your system by emphasizing something that is underperforming in your electronics or de-emphasizing something. I spent years matching very good quality cables and interconnects to the benefit of my system overall. My system is of caliber now I just go up the Transparent hierarchy to match the value of my equipment, simple, easy and each level simply sounds better. Most of my components are around $20K and interconnects ~$2,800.

I have the MIT EVO One bi-wire speaker cables in two of my systems and they are beyond what one could imagine. Image solidity down into the bass and limitless highs. A real soundstage with not only left and right imaging but back to front and height as well. Of course, one does not purchase cables in this price range to put in an average system which goes to say that one has put some real thought into component/system matching and has spent considerable time on the room and acoustics of said room. The payoff is tremendous and well worth it and yes some will scoff at MIT but Bruce has never pulled any punches and is only using his knowledge in the service of music.

From Noel Lee promoting Monster Cable back in the late Seventies to today's Cult of Wire Believers ... with zero hard engineering evidence to back up a company's claims that their product is somehow "better" than the competition!

The only difference between a $200 speaker cable and a $2500 speaker cable is the number of zeroes in the price!

I’ve attended numerous audio expos, worked with my dealers, and demoed a variety of their cables in my home, And to me, there is no doubt of improvements through careful selection of cables that involved moving up to an expensive cables loom in MY system (emphasis added)

I stepped up to the “expensive price strata” cables too BUT ….AND ITS A BIG “BUT” …. Getting that system synergy is not about $$$$. As pointed out by @ghdprentice, big bucks alone is no assurance to audio nirvana.

Your Takeaways IMO:

(1) Capacitance, inductance, materials, connectors, screening, and shielding impact all cables including $$$$ cables, so there really are valid reasons for cables to have different sonic signatures.

(2) As previously mentioned by @nmmusicman, many less revealing systems simply lack the resolution capabilities and will not highlight the differences.

(3) Some people are born with better ears than others, so decide using your own.

Some validly point out the difference that “better” ($$$$) cables made to their systems. The audio forum fans are split in the cable wars about cable upgrades as a last link to audio performance upgrades.

A common voice is “Nah, it didn’t happen …you just wanted to hear an improvement and so you think it did…”

Just like how some want to hear a change, others already have their minds made up that cables make no difference. A key question is whether those people have arrived at that conclusion after thorough and careful audition bespoke comparisons. Expectation bias works both ways.

(4) The overwhelming intuitive advice is to try and demo the cables before buying. So if you experience the positive difference then go for it - Upgrading got me the added dynamics, ethereal airiness, elimination of sibilants / edge, added bass slam, presence and tonal character that was all a quality step-up for the better.

But If you try then and cannot hear that step-up, ….OR ….if you simply don’t feel that added drain on your wallet is worth it to you, then just don’t go there…full stop.

We are generally spared disagreement comparing a $10,000 amp to a $250 amp. But in that same extreme $$$$ comparison with audio cables, we predictably get contrasting opinions including hyperbole in heated argument BOTH WAYS when comparing a $10,000 SILTECH, CARDAS, MIT, TRANSPARENT, or NORDOST models to some 14-gauge generic cable. CANUCKAUDIOMART now warns that waging cable war forum posts will be culled and repeat occurrences will get you suspended.