Sir, so its best to use the 4 ohms impedance switch? rather than the 8ohms, when using a 6 ohms speaker load. much secured if the amp is cooler.
so sir according to you kung pang "audiophile listening" is much better to leave the switch untouch (case of yamaha 8ohms setting) kahit ano pang load ng speakers ang gamitin mo,.... then pag bugbugan naman its better to follow the manufacturers recommended impedance load? ....
hindi ba burden on both end yun (speakers and AVR) ? meron bang noticable difference on over-all audible performance pag nag toggle ka sa impedance switch for what is best for both gears (speakers and AVR)? katulad ng sinasabi ng audioholics na nababawasan daw ang dynamics and overall fidelity.
I don't know whether there is noticeable sound difference if you toggle the impedance switch. For typical listening, I think none. Pag medyo binirit mo na, and you are asking the power of nature to play unusually, meron. For good designed AVR, they are usually protected, so using low-imp load kahit na ka 8-ohm ka, nag ti-trip yung protection niya kapag nag-overdrive ka (that is, if you trust the protective circuit to save you any damage of gears). This condition draws more power than the amp can supply, and can bust your transistors.
On the other hand, speakers have no protection at all, and if you feed it with an amp switched to 4-ohm (which typically brings down the bias voltage), at nirakrak mo nang husto, you are in for a clipping (DC state) - bust una ang tweeter mo, maging lonely ang woofer mo, baka magpakamatay na rin yan.
For your calculated typical listening, leave the switch untouched.