As i begin to reply to your post i'm not really sure where to start. Your first paragraph mentions power output, but i never contended you were having a power issue. Distortion comes from your receiver/amp when pushed to its upper limits. For example, someone has a party and puts their receiver up to the 95%+ volume level to get max sound and instead gets increasing distortion.
This type of effect occurs with many pieces of technology as their upper limits are approached. Efficiency decreases and detrimental effects increase. You could toss in cars and RPM to HP data, planes and speed vs. shear, etc. Home electronics are no different be it computers or receivers.
Hence, what i was implying was that if you were turning up your volume dial to get more volume from your system, you may be reaching that upper limit. What i mean by 'upper' is really quite high as in 95% or more of max give or take a couple of percentage points. Now i don't know what level of volume you were using for listening but it was a suggestion.
I personally own an Onkyo 797 which is very comparable in specs to your Denon 3802 (a nice receiver choice) and neither of us have paid $10,000 for a receiver that may be alot cleaner at higher volumes. Higher quality parts, better engineering is simply beyond us (at least at the present time it appears).
After looking at your room specs, i was also wondering how far away your listening spot was compared to your speakers. Most listeners may sit around 6 to 15 feet away but beyond that, i would imagine the tv would start getting harder to see (not to mention the LCD numbers on your audio equipment). The further away your listening spot, the less volume you should expect of course. Hence, people in the forums who say the speakers put out plenty of sound may be sitting 8 feet away while your own listening position could be double that distance. This is information you never provided in the original post.
I am also confused as to what you are referring to as 'level of output' and 'choice of sub'.
Do you mean to say the volume of your entire system is fine and just the sub-sound volumes are too low?
In regards to the volume differences between dvds and cds, again, what is your source?
DVD players typically list specifications, on S/N ratios, dynamic range, frequency response and sensitivity, separately for dvd and cds. How these values are different within the same player has to do with the DAC and DVD video D/A decoders being separate entities. I'm not surprised at all that you may encounter volume differences between the cd and dvd.
As for the buzzing, it is possible that you have drivers that need replacing but there are several steps you should undertake to remove the playing source as the problem first before deciding this is a design flaw and not something in your setup as you mentioned.
Your suggestion that the company is hiding a flaw that they know about may be a little harsh:
"The comment about "in general" is for the designer who may have made that design compromise...while designing the speaker believing that such a situation...is infrequent enough to not warrant spending an inordinate amount of resources to rectify it"
Ian can of course defend himself and his own company here but i don't believe he would feel he has to. The QS8s are some of the best designed surround speakers that i've heard in my lifetime. That may or may not say alot i suppose.
However, all that aside, I would be glad to try out a test with your song list (which includes the tune that seems to elicit this buzzing sound in your QS8s) with my own setup. Then i can crank up the volume with the same song and speakers but with different source equipment to check for this buzzing noise.
If the buzz is particular to your individual QS8s or source equipment then i won't hear it.
If the buzz is due to a QS8 design flaw then it should be reproduced on my system as well. However the song itself may also be the cause of this problem if it was recorded to actually make such a noise. Very recently some string cello twangs had my thinking there was something wrong with my tweeters in the M60s but it was actually the accurate reproduction of the song that had me fooled.
I am presently using, as previously mentioned, an Onkyo DS797 receiver with a Panasonic CV52 dvd player. I have M60s as mains, the VP150, EP350 and QS8s for surrounds.Please pass along your song info and i can get started.
