@PENG I sit 11 feet away from the stereo Sierra Towers with RAAL 70-20. The room is a 1200 sf basement that is totally underground with a 600sf listening room. The air conditioning is turned off. The RISEPRO Decibel Meter model HT-80A offers the 36db reading at a volume of 1 on the Denon 4700. I was playing NILS Lofgren, Acoustic Live "Kieth Don't Go" on a Denon DCD-800NE CD player. I am the only one in the house at the time.
At 12 on the Denon volume I can easily hear the song and understand the vocal. Even though it's soft. At 3, I can hear the guitar and most of the words but very soft. At one I hear the applause. The vocal is difficult to understand each word but it's obviously still playing at a very low level. It's pretty amazing to me that even at 1 on the dial it doesn't sound silent. Decible meter shows 36.3 reading at 1.
In next test, I used the Denon Audyssey: Levels: Test tone for the front L speaker. At 16 on Denon volume dial the noise is almost gone. At 14 it's so low that if you are not looking for it you will not know its playing. This is with the level in Audyssey set to -2.0db for the speaker and the volume set to 14.
Does any of this help determine how I could use this info to understand how the SINAD readings may apply to my listening room? Thank you!
Since you have run Audyssey auto setup, at you mmp you should be getting about 71 to 75 dB so let's assume 73 dB, with volume at 80.
That means when you turned volume down to 14, the level has dropped by 80-14 = 66 dB.
The test tone is at 73 dB at your mmp, so 73-66 = 7 dB at volume 14 and it would appear you cannot hear the 7 dB at all. This is still unusually good because in my room, the test tone definitely mixed in with the noise floor when I turned the volume down from 0 to -56 or maybe -60 just to be generous to myself, and -60 is about 19.5, so either you hear 5.5 to 9.5 dB better than me, or you also have a quieter room.
Back to your question, it depends on your starting point, that is the peak spl when you listen to music. You know you cannot hear the test tone when it goes down to 7 dB. So it is likely that if you listen to say, music with peak spl from your mmp up to 100 dB (5 dB below reference), then you will likely be able to hear the effects of harmonic distortions that is 100 - 7, that is 93 dB below the fundamental frequency of the signal.
So I think you have excellent hearing and that would put you in the below 20 age group.
Keep in mind, this is test tone. Humans are most sensitive to the 2000 to 5,500 Hz range. That means if you use REW to generate a 1 kHz tone, you may be able to hear the 2nd, 3rd and 4th harmonics at even lower levels.
So to be on the safe side, if you want to be sure harmonic distortions produced by your AVR will be below the threshold of audibility, you probably should play it safe and go with SINAD > 90 dB.
I say play it safe, because if you read Gene's bench test reviews he seemed to have suggested that the threshold of audibility for THD+N is probably around 0.025% and not lower, that is about -72 dB. In his review comparison of the THD+N (balanced input) between the CX-A5100 and A5200 he said:
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"While 23dB sounds like a really big number, it's important to note that the overall distortion level is still quite low for the CX-A5200 model and below the threshold of audibility in my testing."
And his comments referred to the bench measurements below:
CX-A5100:
Brown: Unbal - 90dB @ 1kHz
Red: Bal -95dB @ 1kHz
CX-A5200:
Purple: Unbal -88dB @ 1kHz
Blue: Bal -72dB @ 1kHz
So if you go with that comment, 72 dB SINAD is good. If you go with the results of your experiment, I would again, suggest you stick with >90 dB SINAD. If you have the X4700H, it should get you there no problem.
