audioquest speaker cables and levinson amp

Hi
My system is ML 39,380s,332 Thiel 2.2 I use CZ Gel or Cardas
Golden Cross interconnect. My speaker cables are Audioquest Clear+ or Audioquest Sterling.
My question is the Audioquest Clear work good but when I use the Audioquest Sterling the sound is thinner and seems kind of odd less of everything...
I sent the Sterling to Audioquest to get them evaluated and they did extensive testing and said they were fine.
When I received the back I tried again and got the same sonic result as before.
I listed them for sale and sold them and the new owner sent me a message saying they sounded great!!!!
His system was Classe ca 200 and a pair of magniplanars speakers.
So why didn't these high end speaker cables integrate into my system
I have seem that other people have used Sterling with a levinson amp
And prior to owning the Thiels I had B&W 801 S3 and had the same sonic results using the Sterling Speaker cables