HDMI Vs Digital Optical

None whatsoever. Use a single HDMI cable for best performance. By the way, Yamaha produced an A700 amp in the 80s, so I assumed you mean the Yamaha RX-A700 which is a 7.1 channel system since you're using HDMI.

Hi steaprok, I don't know your case, but I will quote my case with the cable box exclusively.

Among zillion channels my cable box has a couple of HD channels with Dolby Digital 5.1 encoding (HBO HD, National Geographic HD, etc.). While the cable box was connected via HDMI to my avr I only got a 2 channel audio input, but after a thorough read on the cable company's website, they do mention the optical out as the source for 5.1 ch audio stream.

Rushed to the nearest media shop, bought an optical cable and Bingo!, now the avr is receiving the 5.1 input instead of 2 ch stereo only.
Eventhough the HDMI standard allows the transmission of multi-channel audio, my cable company (UPC) provides this service only via an additional optical cable connection.

You may check your cable box as well, though YMMV.

That all depnends on your cable company - only a really nasty cynical company will cripple the cable box like that. Mine for example does provide 5.1 audio via HDMI - all you have to do is select 5.1 dolby output on the cable box menu.

But that is more an issue of cable company policy than whether optical cable sounds better than HDMI. It is unlikely that there is any discernible difference in these two methods of transferring the same audio signal.

Osamede, selecting 5.1 on the cable box was not enough in my case when I had only HDMI connection. The input signal channel indicator on the avr still showed a 2 ch input, while with the optical cable now all the 5+1 indicators are lit.

Can you confirm this in your case, i.e. does your avr with HDMI only show 5+1 incoming channels? Just curious.

Meanwhile, totally agree with you, there is no quality difference between HDMI and optical cable input!

If you are interested in listening to music from either source in a Zone 2 application, you'll need to have analog (RCA) cables connected between each source and the receiver.

You can always test optical vs HDMI. On my Yamaha, I can cycle through audio options. so it's easy to test.

In theory, the bits are the same, for DD, DTS, and two channel PCM. That is, whatever the source bits are, should end up on the other end as the same bits.

In spite of that, in reality I have experienced differences. Such as optical being at different level than HDMI for the PS3 (a different level does not mean the quality was different, and it's not even a guarantee the bits were different in transmission, but it was unexpected.)

Sounds like you have your AVR setup incorrectly, i.e. you didn't turn off the HDMI audio from AVR to TV. Either that or you didn't setup the cable box correctly. For example, on my SA8300 box, I have separate HDMI audio settings for: HDMI/auto, 2-ch or Dolby Digital.

Don't know if it's still the case, but AT&T Uverse cable service used to require optical in addition to HDMI in order to get DD.

Did you hook up the optical along with the HDMI or did you switch to component for the video portion?

My avr is a Denon 2310, so I hooked up the optical along with the HDMI and assigned the opt to the relevant HDMI input.

No, I didn't turn it off, the HDMI audio output is set to AVR, not to TV.

HDMI/Optical/Coax. are all digital signals and provide the same quality (in theory). I've never used coax so I can't speak on it. But from my experience HDMI and optical are identical, there is no difference (at least that I've noticed) whats so ever. HDMI is more convenient as it can carry HD video signal, as optical is only sound...so from a convenience stand point HDMI is more convenient. But sound quality better? I highly doubt it.

If you're talking about a cable/satellite box then yes you will get the same sound thru all 3 types of digital outputs.

Now if you have a Blu Ray player you'll want to use HDMI for audio because you'll get uncompressed lossless audio which is better than what optical and digital coax can provide.

There are some cable companies that do cripple the HDMI audio to only 2 channel, when in fact it is capable of 8 channel output Why they do it, I don't know, but it does happen.

Actually, the theory says otherwise . Digital audio data is a misnomer. Only the sample values are digital. "When" you are supposed to play them, is an analog timing information which the receiver must measure based on the received waveform over the interface cable. That measurement is fraught with issues which tend to be more severe with HDMI and Toslink than S/PDIF although the latter is also quite problematic in the wrong hands. You can read about this at pretty low level of detail starting here: http://www.avsforum.com/avs-vb/showp...&postcount=677

Now, keep in mind that we have this discussion in the context of where the other forum is: $20K equipment and the need for absolutely best fidelity. In the context of having hi-fi sound and is dynamic, etc., what you said is generally true . I just want to make sure that the science is clear.


HDMI has another advantage in that if you are playing Blu-ray, it can carry the full resolution signal. If you try to use S/PDIF or Toslink, you will be forced to a max resolution of 16-bits and 48 Khz which is quite good but may subject the soundtrack to downsampling if it is at a higher rate/resolution.

I stand corrected! But for the purpose of this discussion (low end gear) I believe there wouldn't be a noticeable difference between the three. At least from my experience. Maybe with extremely expensive gear it would make a difference, but for this kind of stuff I doubt it. Just my opinion

denon is notorious for not handshaking properly with some brands of cable boxes (motorola especially)...

handshaking? Can you elaborate? Like it distorts the signal? Don't know about that, I connected the cable box directly to the plasma and it was no different than when I connected it through the Denon. The Onkyo just improved the picture, I don't think the Denon distorts it. Unless you're talking about something else when you say "handshaking"

There's various HDMI issues.

One problem that some people have run into, is signal problems, sometimes blamed on HDCP, the copy protection mechnsim that sits on top of HDMI.

Another issue is HDMI repeaters. A receiver operates as an HDMI repeater. The HDMI document I looked at was very terse about what this means. It says that a receiver should look like a source to a sink (TV) and a sink to a source. But it seemed to be mute on issues such as what happens when a TV is powered off. Does the receiver lose the information? If so, then when the source gets the EDID info from the receiver, it does not include the proper display properties. I had numerous issues with this due to Tivo changing it's setting just because I powered off my TV.

Yet another issue is audio. Cable boxes are bad with this, as is Tivo. When you change streams, like changing channels, audio may be lost for seconds, or sometimes even lost until you change something again - I usually fix this by pausing and unpausing Tivo.

So while HDMI offers the best option for digital video (as conversions are needed with component video,) and the best option for lossless audio, and the simplest wiring, it's not without it's issues.

the term handshaking is what happens digitally when one hdmi device meets another...like the old computer modems.... they talk to each other explaining what kind of signal they are carrying.... since this is still a relatively new technology and is being evolved all the time, not all devices are as compatible as the manufacturers would like... so sometimes there are errors when the devices are communicating (which happens every time there is a channel change or media change) and sometimes you dont get the correct audio or display or sometimes you get nothing at all... this issue is becoming less of a problem as the manufacturers figure it out but it still occurs to some degree....