Headphone cable, what do you do?

Cleeds.

How did Grado know if I had bought from an unauthorized dealer?
I never mentioned any names and they never even asked.

Unless Grado are enforcing that NONE of their authorised dealers are allowed to sell on eBay.
Which on its own is a very narrow minded viewpoint and my opinion of Grado has not changed one jot.

Sgordon1.

Staying away from eBay is not a practical or sensible option in today’s age.

A LOT of major dealers use eBay as it gives a worldwide presence for sales and in today’s modern commerce age just cannot be ignored.

uberwaltz

How did Grado know if I had bought from an unauthorized dealer?

Grado dealers don't sell new product through the e-bay channel. That's not uncommon for premium products. You probably can't buy new ARC, or McIntosh, or Pass through e-bay, either.

Staying away from eBay is not a practical or sensible option in today’s age.

That's a personal choice. Frankly, I've only rarely purchased through e-bay.

Cleeds
And as I said if Grado are restricting their dealers from enjoying more sales via eBay then I still have no time for them.

And if that is the case then that is exactly what they should have stated in their reply to myself.

Of course everyone is entitled to their own opinions viz eBay.

Personally I would never have been able to sell half of my older gear without eBay due to its massive audience.

YMMV

Cleeds
Just as a FYI.

There are 19 listings on eBay right now for Grado products where ALL 19 state categoricaly that they are full authorized Grado dealers.

Just type in the search bar "authorized Grado dealer" …..

Just one example, note the wording in bold at end of the ad!

https://www.ebay.com/itm/Grado-Labs-SR125e-Prestige-Series-Over-Ear-Headphones-Authorized-Dealer/254...


So either they are making false claims and statements or Grado customer service is full of it!

Again I did not mention the dealer I purchased from on eBay in my email to Grado and they never asked me who I purchased from.

So they had no way of knowing if my purchase was from one of these "authorized dealers" or not?

My takeaway from this is that my experience of Grado customer service has been very poor and that if these truly are authorized dealers then do not expect Grado to stand behind them via direct contact.

And that is my final word on this subject.

It's usually pretty easy to find information about warranties on most manufacturer's websites:

"Only products purchased from an authorized Grado reseller will be honored under our warranty program. Grado resellers are not permitted to offer merchandise through any online auction services; hence any products purchased this way are not covered under our warranty program. When purchasing a Grado product please keep all receipts, for they will be needed to have warranty service performed."

This agrees with what you were told about buying the cable on ebay.  I'd say your issue is with the reseller, not Grado.

https://gradolabs.com/company/where-to-buy