"Maybe ZH270 together with MX will change my cable opinion. Any comments?"
My guess from my 6 years experience with the VSM is that the Berning will not offer more forgiveness which is what you are looking for Nr9. To the contrary I think it will reveal the imbalance of the silver cables with the VSM to a greater degree than the Cary. It is an extremely transparent amplifier. As stated in an above post, I have experimented with numerous silver cables and the problem is the upper frequencies become overemphasized and render a leaness to the presentation. The Merlins are, as well, so resolving that this can become a real issue, especially if you are very sensitive to it. The only silver cable in my experience, and its not pure silver, is the Stereovox which doesnt' do this. It offers body, transparency and control with high frequency extension and air without any undo emphasis. I really love the organic wholeness and balance that this cable presents. I have listened to other silver cables which subjectively offer greater bass impact.
I agree, copper cables certainly don't offer the transparency of silver but many do work with Merlins better, at least to my ears. Silver cables I have tried include the following
Blue Marble - ics and speaker
Harmonic Tech Silway -ics
Nordost Vahalla - ics
Stealth Beta - ic's(these were definitely the most transparent of the bunch and conversely the most amusical with the VSM. They were unlistenable after 5 minutes. I had 3 pair on hand. Each added pair made the sound worse)
a few others over the years but the results were the same.
Before you do anything, you might want to listen first with the different feedback settings per Musicpre's suggestion but I am fairly certain you will come to the conclusion that Vahallas and Merlins most likely won't like each other and neither of the amps will have much say about it. I don't know anyone using this combo.
It the problem continues and you want to maintain the transparency of the Vahallas, I would STRONGLY suggest trying Stereovox, especially the 600 sei mk2's and you might want to try their reference speaker cable which I
haven't tried in my system, I'm afraid I'll like it too much and be compelled to buy. I am using the Studio which is a copper cable. The price has come down from the strastophere on these cables to more realistic levels. I wonder what my wife would say about that comment? ;^)
Good Luck and keep us posted on your results