I am looking at buying an Axiom speaker setup. I have a question about the Impedances of the speakers. I am currently looking at getting:

M50x2 or M60x2 (8ohms, still waffling on what I really need)
V100 (8ohms)
QS8x2 (6ohms, "8ohms compatible")

Now my Yahama receiver has two settings for speaker impedance, 6ohm min or 8ohm min. My question is: is it better to run the receiver at 8 ohms since the QS8s are compatible, or should I set my receiver to 6ohm min (and will the 8ohm speakers still work)? I guess I can skip the whole problem by getting the 8ohm QS4s instead, but people sure rave about the QS8s ;P

This question come up a lot.

You want to leave your receiver on 8ohms switch setting, even though some of the speakers in your setup might be 6ohm or even 4ohm (m80's).

Okay that's good to know. Does running at 8ohms reduce the quality of the QS8s (or reduce their lifespan)? I'm not really sure how the impedance relates to the speaker sound quality/power/longevity (although I have noticed that higher quality speakers tend to have lower ohm ratings).

Edit: Nevermind. I did some googling and found a good link about my setting in the Yamaha: http://www.audioholics.com/productreviews/avhardware/YamahaRX-V4600HTp2.php.

"I recommend the "Minimum 8-ohms" setting even for 4-ohm speakers of moderate efficiency (>89dB SPL). Yamaha includes a" 6-ohm" setting to satisfy UL heat dissipation requirements when driving 4-ohm loads, as well as easing consumer concerns about driving low impedance loads. These switches step down voltage feed to the power sections which can limit dynamics and overall fidelity. My advice is to keep the switch set to "Minimum 8-ohms" regardless of the impedance of your speakers and ensure proper ventilation of the Receiver."

Thanks for the help.

Ban, welcome. Yes, points similar to those which the Audioholics review makes have been made here on several occasions. The lower impedance setting is only for satisfying UL requirements and possible legal liability concerns. It reduces the maximum rail voltage which the receiver can supply and therefore the maximum current and power, which the voltage controls, is also reduced in accord with Ohm's Law. You'll have no inpedance concerns with the Axioms which you're considering if the impedance setting is left at 8 ohms.