Thank you for the warm and friendly comments for everybody

Yes, you are right with the Goertz cables. I always read every information before buying anything. I know the oscillation possibility of solid state amplifiers, but I hope that my studio quality Sansui is strong enough.
I connected only the left speaker with the Goertz and compared the sounds of the two sides. There is a sensible difference relatively to my old standard speaker cable. After about a ten hours listening of music and becoming more and more brave, so turning the power to higher, once I heard something abnormal in the sound and this happened repeatedly. I turned off the Sansui right away. I remembered the possibility of oscillation and also the solution: the Zobel network. I went to the Goertz webpage and searched for the Zobel network. I found it, it was like a simple short cable and the price was 20 USD. Fortunately I did not ordered it, because I remembered that my iPad had difficulties downloading Internet files parallel listening music. It was not the case before. So I decided to check the sound with my SACD player. And I was right: the Sansui is a powerful, stable amplifier and the iPad had difficulties with the many opened webpages. I restarted it to free up memory and everything become normal. So now I can enjoy the almost maximum power on a very good quality.
To tell the truth, I read good references about using Sansui and Infinity Renaissance with silver Goertz cables. So, maybe this will be the next step when I will have enough money.
Excuse the long message.