Subject: Does the power of a magnet reduce when around other magnetic metals ?

I want to know if a magnet used on a speaker/subwoofer will loose a part of its power if it is in contact 
or within close proximity of a metal such as steel, as opposed to something like aluminium that is not 
magnetic. Meaning that if you were using the speaker and it was mounted or close to steel would some 
of the magnetic force of the magnet on the woofer be used on the steel surroundings, meaning less of 
its power is actually used on the voice coil of the woofer, in which case it would be better to use 
aluminium which will not take away any of the woofers magnetic power ?

Thanks
andrew

Re: Does the power of a magnet reduce when around other magnetic metals ?