Is aluminum wire any good as speaker wire?

Aluminum wire is just that...cheap. It is inferior to copper in most aspects of concern, especially having higher resistance that get worse over time as more aluminum oxide forms on the exterior of the wire where most electrons travel. A run of 30ft will have a much higher resistance, a heavy guage will help to compensate.
Unless you are an audiophyle, you most likely will not be able to tell the difference except for an increased work load on the audio amplifier.
T

"increased work load on the audio amplifier"

How much?  dont want to burn it out.

Thank you jhance, that jibes well with my experience.  AL wire is only a danger when overloaded with current for the gauge of the wire.  I had heard that there is not a huge signal loss, tho more than copper, and I was hoping it would not be that much loss.  After all, the utility companies now all bury aluminum wire in the ground to run their main power feeds to subdivisions, the thing is, they have learned to make it thick enough not to be in danger of burning up.  I will proceed with the AL install and let you know how it goes.  Stay on the thread until tomorrow, then you can leave - and thanks again.

18g wire is 56% of the cross sectional area of 16g.
Copper resistivity is 63% of aluminium resistivity.
Therefore the resistance of a given length of 16g Al wire is significantly less than that of 18g Cu.
Go for it.
The only other caveat is that aluminium is less ductile than copper. It's not an issue if you treat the conductors with reasonable care. i.e. don't bend it into sharp curves more than once - but you shouldn't do that with Cu speaker wire either. You get away with it with normal electrical power cords because they're not single solid conductors, they're composed of many small strands.

thank you vallis, I would have split points with you, I will catch you next time, that is very useful info.

You're welcome :0)

BTW, I would like to let you both know I got the aluminum wires hooked up and the speakers sound great, full impedance range  I think you are right vallis, as long as the wire is one step thicker, it should work just as good.  Many thanks again.