Signal degration over length, source vs. output ?

Generally longer interconnects are better than longer speaker wires.

What distances we're talking about? Where is your stand and where is your speakers? What are the speakers and what are the input/output impedances of your preamp and amps?

The lengths you describe are not a real concern either way but I still prefer shorter speaker cables.

The reason for my preference is that the connection between the preamp and amp is impedance-defined for the transfer of voltage and, assuming decent cable and appropriate impedances of the preamp out and power amp in, the only loss will be voltage. That is easily compensated for by a little touch on the VC.

The amp to speaker interface needs to transfer power (voltage and current) and the input of the speaker (almost any of them) varies widely in impedance. Increasing cable length increases resistance and reduces power transfer but also does so in a manner that varies with frequency due to the varying load.

All that assumes near ideal equipment and really long runs. Your setup is not stressful.

Actually, my concern is the harmonic change due to very long speaker cables rather than power or voltage losses. In addition, living with a 10meter run for one or the other, I have experimented with both and found my preference. Of course, I generally use a preamp with a <50ohm output impedance and excellent voltage output.

In the OP's case, (and indeed in any other), best advice is to try both ways if one can.

I have a tube preamp with <50ohm output impedance as well.

Sonic Frontiers Line3. Output impedance 45ohms SE, 90ohms bal.