Silver cables or copper?Any opinons.

use both.

You are going to have to provide a little more info if you want any serious suggestions....

Maybe list your system to start, then budget and where you think your first cable change might happen

AES Standard rates copper as Standard for Signal transfer ability (=100%), Silver for example is 106, gold is around 90 and everything else is much worse. Silver can carry 6% more Information than anything else.
When the unit has very cheap RCA input plugs (brass with gold plating for example), they are in the area of 60, that means, they reduce any input signal by min. 40 % from what is possible. That is the real problem, not cable rolling (most have good connectors but here it is the same, it is not magic, it is knowledge).
The next interesting fact is, when there are two options, for example RCA and XLR, or RCA and DIN, which one has the better amplification stage?

Most manufacturers try to save money wherever it is possible, (nearly) no one uses real high quality RCA in- outputs (or silver wire inside)....the problem is not the manufacturer, the problem is the mark up for the following distributor chain.
I changed all the RCA in-/outputs from my Lamm Preamp/amps to the best available ones and the difference must be heard to believe ... but that was really expensive.

11-04-14: Syntax
AES Standard rates copper as Standard for Signal transfer ability (=100%), Silver for example is 106, gold is around 90 and everything else is much worse. Silver can carry 6% more Information than anything else.
When the unit has very cheap RCA input plugs (brass with gold plating for example), they are in the area of 60, that means, they reduce any input signal by min. 40 % from what is possible.

Syntax, can you provide a link to that "AES Standard," which backs up those numbers and also defines exactly and clearly what is meant by "signal transfer" and "information carrying" ability?

The only thing in any of those numbers which to me makes any sense whatsoever is the 6% difference between silver and copper, which for a given gauge approximately corresponds to their difference in resistance per unit length (i.e., resistivity), and its reciprocal, conductance per unit length (i.e., conductivity).

All of the other numbers you cited appear to be either incorrect (i.e., the conductivity of gold is considerably less than 90% of the conductivity of silver and copper), or, frankly, misleading mumbo jumbo (i.e., cheap RCA plugs "reduce any input signal by min 40% from what is possible").

Also, regarding the 6% of so difference in resistivity and conductivity between silver and copper, a point to keep in mind is that that difference can be compensated for several times over by simply going one gauge size larger in copper. It can also be compensated for by simply making the copper cable 6% shorter than the silver cable. And in the case of line-level interconnects, a 6% difference in resistance will be utterly inconsequential anyway, as it will amount to a completely negligible fraction of the impedances of the components that are being connected. And the same goes for speaker cables under most although probably not all circumstances.

Therefore if in fact there is a general tendency for silver cables to have different sonic characteristics than copper cables, that 6% difference in resistance per unit length is almost certainly not the reason.

Regards,
-- Al