Kind of a dumb question...

Use the best one from your source to the pre.
Good listening!

what do you mean by "not of the same quality" ??

if one cable is better than another, in what way ??

can't answer this question without the facts.

without a criterion, cables are different, not better than each other.

i have reviewed many cables and while i hear differences, i would not say one brand is better than another.

perhaps you prefer one to another. why ?

i will give a general perspective:

consider the interaction between cable and component.

as you said, it is easy to test the cables.

just use them between dig. source and pre and pre and amp.

there are only 2 possibilities. one will be preferable.

In two of my three systems the better sound is achieved between my amp and preamp. I do believe at times it’s a system dependent thing.