I bought some new Swan 4.1 speakers that are rated 4 ohms. I was planning to get a Behringer A500 to drive them but didn't get around to purchasing before they got here. Now I hooked them up to a cheapy Sherwood RX-4105 and it seems to be driving them just fine (it is only rated at 8 ohms). The guy at the Audio Insider said that these speakers are rated at 4 ohms "nominal" and that really any 8 ohm receiver would be able to drive them. It appears that he was dead on.
Here is my conundrum: I have to get a new receiver anyway (I need a receiver that I can plug my HSU STF-2 into...thanks Seth=L
). Should I just try and get a decent mid-grade receiver (I'm thinking Onkyo or Denon) or should I go ahead and get a refurbed Denon with preamp-outs paired with the Behringer A500 anyway? Will the extra juice be worth the extra 200 dollars? I don't want to buy something just to say I have it, I am hoping there will be some kind of significant improvement in overall sound if I get the A500 or will it be overkill?
I do not know what the impedance curve is on those speakers, so it is difficult to say. You see, impedance of a speaker varies with frequency. The "nominal" rating is what the manufacturer claims is what you can pretend the impedance is when matching with an amplifier. Sometimes they like to inflate the number in order to get you to think it is okay to use it with a wider range of amplifiers (I remember reading about some speakers years ago that were rated as 4 ohms nominally that had impedance dips below 1 ohm!, though that is not the norm). And with amplifiers, they may or may not be able to handle something a bit lower than their ratings suggest.
Generally speaking, you can get things to work, for a while, if they are mismatched. But using low impedance speakers on an amplifier puts additional stress on it, and generally causes it to run hotter. This may (or may not, depending upon all of the particulars) cause the amplifier to fail prematurely, sometimes very quickly. So, if you want to be safe, you will want an amplifier that is rated for 4 ohm speakers. You may not need it, but if you do and you don't buy a better amplifier, you run the risk of an early death for your receiver.
Sherwood, by the way, makes equipment for other brands, too, only they typically sell for more money that way. Typically, or at least in the past (I have not checked into this recently), Sherwood offered a good product for their price point. So it might not be worse at dealing with low impedance speakers than what you are planning on buying.
