This is not directed at anyone in particular, it is just conversation.
When I started working this up I thought this exercise would show the Denon 1911 would be more than capable of driving the RF-62's to very loud volume levels without any significant strain.
While there are plenty of assumptions in this post that could be (haha... will be) ripped to shreds I am no longer convinced in my original assumption about the 1911
If you are pushing the volume up to high levels, the RF-62's sensitivity is not as advertised, and they get below 8 ohms you can run out of headroom pretty quick..
So here it goes.
I could not find a review of the Denon 1911 with measured data, but there is one for the 1612 (lower model) that is rated by Denon at 75 watts into 8 ohms, 5 channels driven.
HT measured the 1612 output, two channels, 8-ohm loads, 0.1% distortion at 103.9 watts and 1% distortion at 118.5 watts.
Into 4 ohms, 0.1% distortion at 73.4 watts and 1% distortion at 141.5 watts. (the 4 ohm data seems a little off to me but it is a cut and paste from the website so it is what it is)
With Five channels driven continuously into 8-ohms the 1612 achieved: 0.1% distortion at 71.5 watts and 1% distortion at 79.8 watts.
Conclusion of this is that Denon has not exaggerated the output power of the 1612 and I will make the assumption that the 1911 is not exaggerated either.
The 1911 is similar with a rating at 90 Watts, 8 Ohm, 7 channel(s) and 125 Watts, 6 Ohm, 7 channel(s).
Might as well make it easy http://www.calculatoredge.com/enggcalc/ohm%27s-law-calc.htm
Using Ohm's law, 90 watts into 8 ohms is 26.8V @ 3.35A
For this conversation I am using an output power of 64 watts because it is the highest even multiple (without exceeding the 1911 specs) when you go through the output power doubling for 3dB increase in SPL exercise.
The 1911 should easily achieve 64 watts with plenty of overhead left, 64 watts into 8 ohms is 22.6V @ 2.8A..
Klipsch rates the RF-62II as 97dB @ 2.83V / 1m for sensitivity. Rating sensitivity with voltage instead of wattage can be tricky to the consumer, 2.83V @ 8 ohms is 1 watt but at 4 ohms it is 2 watts so right there the potential for specmamship is on the table. The Sensitivity may very well be 97dB across the frequency range if 2.83V is held constant.
I do not know if the sensitivity rating is optimistic or not but there is plenty of feedback in this and other threads that this is the case.
So for conversation purposes let's use 97dB and 90dB as baseline sensitivity numbers.
If 97dB sensitivity is the right answer 64w = 115dB SPL and 90dB sensitivity works out to be 108dB.
There is a lot of difference between those two numbers and keep in mind this is at 1 meter from the speaker so if you are 12 to 15 ft away you may need close to 108 output at 1 meter to get reference level at the listening position.
The real world sensitivity will make a huge difference in the amplifier power requirements.
If the volume of the AVR was set to produce nominal 64w into 8 ohms that would roughly make the output voltage of the amp 22.6V with output current of 2.8A.
The question is can the 1911 hold the 22.6V, on the output if the RF-62's are less than 8 ohms ?
22.6V into 8 ohms = 2.8A.(22.6V x 2.8A = 64W),
22.6V into 6 ohms = 3.8A, (22.6V x 3.8A =85W),
22.6V into 4 ohms = 5.6A, (22.6V x 5.6A = 127W),
22.6V into 3.8 ohms = 5.9A (22.6V x 5.9A = 134W),
You can see where the 1911 will be hitting the upper limits, it does not take much of a dip in the speaker resistance / impedance to really jack up the current requirements.
Of course this is a pretty simple description, and considering text books have been written around this subject matter take this for whatever you think its worth.
Is the AVR contributing to a harsh sound ??
I don't know, but if you are listening at high volume it could be.