Welcome to the forum!

Is there any particular reason you wanted them stacked? Unless they are powered by two completely independent amplifiers, you will not gain anything.

As for cable lengths, unless one if 5 feet and the other 100 feet, the speed of electricity would make the difference inexistant (not just 'inaudible', but well below the physical resolution of our ears).

If I did not answer your question, just wait and someone else will come and chip in.

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