mahgister,
"My experiments comes only from my desesperation because I cannot afford Hi-fi sound..."
What exactly would mean "affording Hi-fi sound" in this case? Is it a number/price attached to components you would buy if you had means? Is there a certain number/price that you think you could invest? Some highest limit?
I have an impression you enjoy this hobby of crystals and other unorthodox tweaks and that the road is actually the purpose. However, if you are really focused on final product, sound in this case, you may have better return of your investment and reach your perceived goal sooner, by building the system first. Starting with basic items (source, amplification, transducer) rather than collecting rocks. That is not to say that playing with whatever tweak you desire is not fun, but that achieving desired result is, to say it politely, somewhat dubious.
There are many contributors on this forum who bounce around names of their equipment with prices way into the category of "just because I could". Many people have extra pieces stashed somewhere in their basements, closets, and under the beds. Some of those items may, objectively, be closer to "Hi-fi sound" you mentioned. Sometimes, just asking may be enough. There are people who feel bad throwing perfectly functional equipment away, do not have any interest in extracting the last penny out of it by selling, and have no more need for it in the first place. They may be happy to give it to a good home.