Re: tower speakers advice
4 Ohms is the nominal (sort of baseline) resistance the speaker offers to the amplifier. This can and does change depending on the speaker and can go much lower, rarely higher.
Remember the old electrical equation..
Well, R is resistance, therefore for a given voltage more current is required for four than eight Ohms with the same voltage, so while it maximizes Wattage (VxI) it requires more I (current) for the same V (voltage) making an amp put out much more current, the very high end receivers are designed to handle this, but mid fi might not do as well.
In general, the lower the resistance of a speaker, the harder it is to drive effectively, and can cause excessive heat production and overload if the amp isn't designed to handle it.
Ken Taraszka, MD