Hi Phil: this is all about synergy.
If it was me: I'd first try each cord, one at a time, on your preamp only. Leave stock cords on the other equipment (assuming that they've been previously running as such). Play around with some various software material for a few days. This will give you a feel for the performance that each cord provides -- but on the preamp only. Then repeat the same tests on your amp only. If you're lucky, you'll prefer the different cords, one on each component. But you may prefer to have two of the same cords. That is of course un-testable, because you only have one of each. Also be aware that when you put the two of them together then something different may occur as they work in combination for the first time. Again it's all about synergy.
However, be aware that connecting those cords to your amp or digital source won't necessarily produce the same sonic signature as on the preamp. Cords & cabling are so very system & component dependent. Synergy - I can't repeat that enough.
Be aware that silver cords generally tend to sound brighter / more detailed/ thinner than copper cords sound. You won't necessarily experience the same phenomenon, but you may. In some rigs & on some components that sonic signature is desirable, on others it is not. Your ears will tell you. Also be aware that, as mentioned, some smaller gauge cords are made only for source components (much less current consumption) so you need to determine what your cords are built for, typically determied by wire size.
Let's not forget about your interconnects & speaker cables. Same issues: synergy with the particular component, & synergy as they combine to work together. This is not an easy thing to work out. And once that you do work it all out, then if you go & change any one thing (say you upgrade the speakers, or speaker cable, or interconnect) that one action can change the balance which you have achieved. At that point you may be almost, but not quite, back to square one. Have fun - you'll get there eventually. When you do, that's when you decide to sell off part of your used cord & cable collection, perhaps retaining some of the favorites because as I said, you'll probably be doing this again someday.
If it was me: I'd first try each cord, one at a time, on your preamp only. Leave stock cords on the other equipment (assuming that they've been previously running as such). Play around with some various software material for a few days. This will give you a feel for the performance that each cord provides -- but on the preamp only. Then repeat the same tests on your amp only. If you're lucky, you'll prefer the different cords, one on each component. But you may prefer to have two of the same cords. That is of course un-testable, because you only have one of each. Also be aware that when you put the two of them together then something different may occur as they work in combination for the first time. Again it's all about synergy.
However, be aware that connecting those cords to your amp or digital source won't necessarily produce the same sonic signature as on the preamp. Cords & cabling are so very system & component dependent. Synergy - I can't repeat that enough.
Be aware that silver cords generally tend to sound brighter / more detailed/ thinner than copper cords sound. You won't necessarily experience the same phenomenon, but you may. In some rigs & on some components that sonic signature is desirable, on others it is not. Your ears will tell you. Also be aware that, as mentioned, some smaller gauge cords are made only for source components (much less current consumption) so you need to determine what your cords are built for, typically determied by wire size.
Let's not forget about your interconnects & speaker cables. Same issues: synergy with the particular component, & synergy as they combine to work together. This is not an easy thing to work out. And once that you do work it all out, then if you go & change any one thing (say you upgrade the speakers, or speaker cable, or interconnect) that one action can change the balance which you have achieved. At that point you may be almost, but not quite, back to square one. Have fun - you'll get there eventually. When you do, that's when you decide to sell off part of your used cord & cable collection, perhaps retaining some of the favorites because as I said, you'll probably be doing this again someday.