So your speakers are about 8 feet apart, right?
Well you're right about all the extra speaker cable, to say nothing of the extra money if it's decent cable. (Because if one of them would be over 10 feet, it would be good to have them the same length.)
Personally, a better way to do it, both in terms of economics AND sonics, would be to place the amps between the speakers using a longer pair of ICs from preamp to amp (I guess about 10 feet based on your information?) and then a pair of 6 foot +/_ speaker cables. Or you could place an amp next to each speaker (but using two ICs the same length) and use really short speaker cables, maybe 3 footers. That would be the best IMO.
If you can used balanced XLR ICs to connect the preamp with the amp, that is desireable, but not essential.
Well you're right about all the extra speaker cable, to say nothing of the extra money if it's decent cable. (Because if one of them would be over 10 feet, it would be good to have them the same length.)
Personally, a better way to do it, both in terms of economics AND sonics, would be to place the amps between the speakers using a longer pair of ICs from preamp to amp (I guess about 10 feet based on your information?) and then a pair of 6 foot +/_ speaker cables. Or you could place an amp next to each speaker (but using two ICs the same length) and use really short speaker cables, maybe 3 footers. That would be the best IMO.
If you can used balanced XLR ICs to connect the preamp with the amp, that is desireable, but not essential.

