Originally Posted by mtn-tech
Sensitivity seems like the first obvious answer, but when I looked them up your mains are actually higher sensitivity (89 vs 88 according to Polk web site). The next most obvious answer is distance from the listening position - sound pressure levels drop quite quickly as distance increases - are your surrounds much closer? I suspect that they are. Stand an equal distance from both speakers - do they still sound louder?
The part I don't know about is running your automatic room EQ - I believe that this should set the channel trims so that all the speakers are the same volume at the primary listening position. Have you tried turning this off and setting the channel trims manually with an SPL meter or a $1 SPL app on your phone?
I also like 5 channel stereo mode when doing something besides critical listening - when sitting down and doing critical listening I go back to 2 channel mode. I just like the additional SPL / room filling sound you get with all 5 / 7 speakers going at the same time.
Maximum power is only needed when the input signal reaches its maximum, which is almost never and only for an instant - so called "crest factor" you can search AVS for the many posts mentioning this. Doubling the power will make a barely perceptible change in the volume level - it takes 10x the power to double the perceived volume. Additional power isn't going to change this - but an amp with higher input sensitivity would change things. If your AVR amp delivers 10 watts of power to your speaker with a 200mV input and an external amp delivers 50 watts to the speakers with the same input - the amp will make the speakers seem louder - even if the amp is "smaller" and has a lower maximum power output. Years ago I had an Onkyo AVR with 120w to the fronts and 40w to the rear - and yet the rear speakers were louder. I suspect the rear channels had a higher input sensitivity and / or the rear speakers were more sensitive - when all the speakers are only receiving less than 5 watts each (normal listening volume) it doesn't matter what the maximum power of the amplifier is.
But again, the channel trims should be adjusting for any different amp sensitivity (which you probably don't have with a modern "same power to every speaker" AVR) or different speaker sensitivity.
This is an AWESOME response! I ended up just downloading a spl tester on my phone, and found that when running test tones, they are all averaging 80 db... so thats good! Auto room eq is doing its thing!
Originally Posted by mtn-tech
If your AVR amp delivers 10 watts of power to your speaker with a 200mV input and an external amp delivers 50 watts to the speakers with the same input - the amp will make the speakers seem louder - even if the amp is "smaller" and has a lower maximum power output.
Regarding the input sensitivity thing, that kinda explains what I was wondering regarding this point. How can I find out if there is variance between these numbers? When looking at the specs for the 4520, I'm not sure what I'm looking for, and the same thing for the Emotiva-XPA2. My guess is that being a higher quality amp, the EXPA2 would probably have more(?) input sensitivity, therefore changing the dynamics slightly.. Probably also a big assumption. But again, if I were to calibrate for the room, I guess it would end up working out so that the levels were adjusted somehow, therefore changing the overall levels.. which gets me to what I posted below
Originally Posted by NuSoardGraphite
If you click on the link I provided above, it explains what Audyssey does with the surrounds. They provide an adjustment in Dynamic EQ called "Reference Offset" that adjusts the volume of your surrounds based on how loud you want them. Apparently Audyssey boosts the volume of the surrounds specifically so that subtle surround content is more audible, but this has an effect on the volume of the surrounds if you play multi-channel music or like to use Pro-logic or DTS music modes. When using All-Channel Stereo, the surrounds will be obviously louder than the mains in this case.
This is definitely true. I actually tested it out by turning Dyn-EQ off while in Multi Channel Stereo mode and found that the levels of the surrounds dropped to an overall quieter level, similar to the fronts while in normal stereo mode. HOWEVER, is the dynamic EQ also doing something to my fronts while in MCStereo mode? When listening closer, it sounds like I have a bit more overall bass response from the fronts too while at lower volumes while in MCStereo mode, they still don't sound as relatively loud as the surrounds with DynEQ on, but they sound different than when in normal Stereo mode.
So here's my next question - while in stereo mode, is dynamic EQ less prevalent or disabled somehow? When measuring using my new handy dandy SPL meter on my phone, I get exactly 10db higher level with MCStereo on. When I turn MCStereo off and switch to Stereo, I need to turn the receiver up 10db to reach the same SPL level. As you can imagine, the bass response is lower in stereo than MCStereo.
Any more thoughts on this?
Btw, you guys are geniuses. Thanks again!