Ok, when I was building my crossovers, one of them didn't work and I was able to track it to a part where the solder got in the way of the wire, I redid it and it worked.
Also, from Wikipedia "2.No-clean fluxes which are mild enough to not "require" removal due to the non-conductive and non-corrosive residue.[4] Performance of the flux needs to be carefully evaluated; a very mild 'no-clean' flux might be perfectly acceptable for production equipment, but not give adequate performance for a poorly controlled hand-soldering operation. They are so-called "no-clean" because the residue left after the solder operation is non-conductive and won't cause electrical shorts; nevertheless these fluxes leave a white-color residue like dilute bird-droppings. which is plainly visible. Since the presence of discernible flux residue on circuit boards is a defect for all three classes of electronic circuit boards (ranging from cheap consumer electronics to high-reliability, mission critical applications), these sorts of fluxes must still be cleaned as with all hand solder work, typically brushing with 99% isopropyl alcohol as the solvent and lint-free non-synthetic (eg cotton) wipes"
so there is non-conductive solder, I'm not completely off my gourd.
Anyway, I just really can't see how this could be difficult. It looks like you snap some connectors together and solder some wires.
And not offended guys, even if that was your intention. It's cool.