I use spades w/ a mechanical(crimped) connection, the advantage is 1) it creates a large gauge cable which has multiple advantages(some explained here earlier by EEman). It is known that electrons flow on the outer surface of a conductor, so the more surface area you can provide, the lower the resistance to the electron flow you will have...Lower impedence, and 2) it is a low inductance self-shielded path as is the point of cat5. 3) its cheap as hell to try this on your own and compare for your own ears as opposed to so many other audio upgrades.

So to answer your question, neither of the first 2 advantages exist with lampcord since your using smaller gauge wire with no low impedance or inductance advantages inherent.