4-ohm setting with 8 ohm speakers

A 4 ohm setting increases the impedence that the amplifier sees relative to an 8 ohm setting. Therefore, fewer demands are placed on the amplifier and therefore if the 8 ohm setting is too demanding for the amp it will sound better on a 4 ohm setting. The principle is the one that applies to Paul Speltz's automformers which increase the impedence that the amp sees and will improve the amp's performance up to the point where the impedence is great enough so that it limits the potential of the amp. It's a matter of matching amp to speakers. A more muscular amp than the ones you have auditioned might reach its potential better on the 8 ohm setting. It's an interesting and instructive excercise.

This doesn't make sense to me and what Arnettpartners said doesn't make sense either. So just accept it as one of those weird audio interaction anomalies that works for some unexplained reason. Perhaps the maker of your amp or the maker of the speakers could shed some light on this.

Personally I wouldn't lose sleep over it. I'd just use the amp on whichever speaker taps sound best with your speakers. Surely it won't hurt anything.

If you find out the actual reason down the road shoot me an e-mail and let me know.

Plato, then what is the purpose of a 4 ohm-8 ohm option on an amplifier? Lynne

I have experienced this too. I believe it comes down to personal preference.