Is 2.0 CH Out Necessary When Using 5.1 CH Out?

[Ronnie 1.8]

Re: my Denon DVD2910, I just noticed that my FL and FR channels (of 5.1 channels) seem to be active, as well as the CD L/R output, when playing a CD. I change my receivers input from "CD" (using source direct) to "ext in" (which is automatically source direct), and hear no difference. When choosing "ext in", The 2910 indicates 2 channels are being output, as expected.

Considering this, why is 2.0 ch out needed? Why not simply use the 5.1 ch out?

Cheers...

[ThomasV555]

Your receiver may (most likely) be able to deal with 2 channel analog better than 6 channel.

[Ronnie 1.8]

Just got an answer from Ray Adams of Audioholics. He said both outputs on my particular player (probably common w/ many players) are using the same DACs, so sound will be identical. He said the only potential advantage of using 2 ch outputs for 2 ch CD's is that the 5.1 ch output may not be able to utilize a "direct" path, bypassing all decoders and video circuitry. My Denon AVR3805 does have a "Pure Direct" mode that can be activated when using the 5.1 ch outs. So in my case, there is no advantage whatsoever of using the 2 ch outs.

[thehun]

Most cases the 2 ch output is redundant, and unless your receiver's 6 ch input is differ from the regular analog inputs[like digitizing it] you should get identical results.

[Sonic icons]

Many functions of the receiver that are available with the 2-channel analog ("RCA" or "red & white") inputs may not be available with the 5.1 channel (or 7.1 channel) analog inputs. In other words, you may lose access to those functions when connecting the CD player outputs to the "FL" and "FR" of the multichannel analog inputs (of course, whether this is a concern depends on which receiver functions you want to use). I expect the details vary from one receiver to another. On my Marantz 5500, the following functions are not available with the 7.1 channel analog inputs:

[list=1]
Bass management (direct low frequencies from other channels to subwoofer)
Speaker distance compensation / time alignment
Matrix surround processing (incl. Dolby Pro Logic IIx, DTS Neo 6, Circle Surround II)
Listening through headphones
Bass and treble tone controls
[/list]

Speaker level adjust is a special case: my receiver (and I think other recent Marantz models) has a 2nd, independent set of level adjustments for the multichannel analog inputs. However, the receiver can't generate "pink noise" test tones to calibrate the level adjustments for the multichannel analog input, so a disk with test tones (like Avia) is required to do this calibration (have the Avia disk but haven't gotten around to it yet).

[Ronnie 1.8]

[QUOTE=Sonic icons]Many functions of the receiver that are available with the 2-channel analog ("RCA" or "red & white") inputs may not be available with the 5.1 channel (or 7.1 channel) analog inputs. In other words, you may lose access to those functions when connecting the CD player outputs to the "FL" and "FR" of the multichannel analog inputs (of course, whether this is a concern depends on which receiver functions you want to use). I expect the details vary from one receiver to another. On my Marantz 5500, the following functions are not available with the 7.1 channel analog inputs:

[list=1]
Bass management (direct low frequencies from other channels to subwoofer)
Speaker distance compensation / time alignment
Matrix surround processing (incl. Dolby Pro Logic IIx, DTS Neo 6, Circle Surround II)
Listening through headphones
Bass and treble tone controls
[/list]

Speaker level adjust is a special case: my receiver (and I think other recent Marantz models) has a 2nd, independent set of level adjustments for the multichannel analog inputs. However, the receiver can't generate "pink noise" test tones to calibrate the level adjustments for the multichannel analog input, so a disk with test tones (like Avia) is required to do this calibration (have the Avia disk but haven't gotten around to it yet).[/QUOTE]Some good points, here. I was thinking only of DVD player functionality, but you list some things from the AVR pov I hadn't thought of. On my Denon AVR3805, from 7.1 inputs, I do have bass management, speaker dist compensation, don't know about matrix surround processing, headphones (good one, I'll have to test), don't know about tone control. Thanks!