4 Ohm Speaker with an "8 Ohm Minimum" Reciever

Probably not but you can add a 4 ohm resistor to the speaker wire if you are really worried. This was done in the very early days of transistors on occasion. What effect it would have on the sound I have no idea.

A 4 ohm resistor in series will soak up half the power sent to the speaker and release it as heat. You may not be able to get enough volume out of the system. Your resistor also needs to handle the power. I'd suggest a power rating of at least P*.707*.5, where P is the receiver rated max power.

If you hook up the speakers directly the receiver may run hot, its protection circuitry may trip, or at worst case you could damage the output stage.

Thank you all for your help. I will try installing a resistor, and call NAD as well.

I drove a pair of 4 ohm bookshelf speakers for years with various "8 ohm minimum" receivers with no adverse consequence.

I was always careful not to crank it, but with a small box speaker I doubt it will stress the receiver much at all.

A resistor is not a good solution. Besides wasting a lot of power, it will cause the frequency response of the speakers to deviate from flatness in proportion to the variations in the impedance vs. frequency curve of the speaker. It will also severely reduce damping factor, degrading bass performance.

I notice that Audio Advisor sells a package consisting of the L54 together with PSB speakers which are specified as 6 ohms nominal, 4 ohms minimum. Also, it would be unusual for an amp or receiver to be designed to truly be limited to 8 ohm speakers. I suspect that calling NAD and also Googling to see what other speakers people have used with the L54 may end up supporting the conclusion that the manual is incorrect.

Regards,
-- Al