Analog VS HDMI on a 1570

[chanlon]

Recently, I've been comparing lossless audio played on an Apple TV vs a CD played through the analog input of a Rotel 1570 processor.

The Apple TV's audio output was connected via toslink while the Oppo BDP-83 via analog cables. Comparing 3 tracks, I could easily distinguish the CD from the Apple Lossless audio file. The CD always had a much better soundstage that allowed instruments and strings to play cleaner and more identifiable.
It seems that the analog input on the Rotel (or Oppo CD player) sounds much better than the internal Burr Brown DAC's (or Apple TV). Well at least to my ears.

This got me thinking.....I've been debating upgrading the Oppo to the SE series. Would it be safe to say that 2CH and multi-channel audio "should" sound better than the Rotel DAC's as well if connected using the 7.1 analog input? Especially if I upgrade to the SE model? I don't care much for the benefits of HDMI. I don't mind having gobs of cables since HDMI handshaking seems to never settle.

Any opinions out there? Has anybody else compared this model?
What would I really be foregoing using this method? Prob. the superior bass management of the Rotel?

[maxwebster]

You need to compare the digital output from the oppo to the analogue output from the oppo - no other comparisons would be much help.

[srb]

You need to compare the digital output from the oppo to the analogue output from the oppo - no other comparisons would be much help.

I would agree with that, you want to use the same source.

You may also want to compare the Oppo's optical and coaxial digital outputs to each other, as it wouldn't be the first time a DAC sounded better on one type of digital input than another (and in my experience, usually the coaxial).

Steve

[kmcheng]

You need to compare the digital output from the oppo to the analogue output from the oppo - no other comparisons would be much help.

Hmm.. I don't think I am following that. Why would the digital output from an AppleTV sound different than the digital TV fo the Oppo? Aren't they all just passing 0's and 1's? Or would AppleTV actually miss some bits? Am I missing something here?

[srb]

It may very well be that the DACs in the Oppo are better sounding than the DACs in the Rotel.

But one of the specifications of digital audio transmission is jitter, or the minute mistiming of the digital bits relative to each other, measured in picoseconds. The Apple TV and the Airport Express are both known to have a higher jitter spec than a lot of other devices.

To get a better sense of the differences in sound between the DACs, you should use the same source, the CD player. As I mentioned, a lot of people have also found that when comparing the optical to the coaxial digital output of a CD player (or in my case, my PC, which also has both outputs), that one sounds better than the other.

Why would these two types of digital outputs sound different? Well, they are both sending 1's and 0's, but the jitter spec might be different out of the coaxial output versus the optical output. Also an optical output has to convert the electrical pulses to light pulses which are converted back to electrical pulses by the optical receiver at the other end, a conversion process that a coaxial connection doesn't have to undergo.

Without getting into a heated cable debate, some hear audible differences between coaxial cables, but there can be even greater differences between optical cables, when comparing one with realtively cheap plastic fibers to one with high quality polished glass fibers.

Steve

[maxwebster]

Hmm.. I don't think I am following that. Why would the digital output from an AppleTV sound different than the digital TV fo the Oppo? Aren't they all just passing 0's and 1's? Or would AppleTV actually miss some bits? Am I missing something here?

Believe it or not, the "transport" is an important element in the process of converting 0's and 1's stored on media into analogue. Some DACs play nicer with certain transports, which is why it is common for a lesser DAC to sound much better than it's more expensive, newer, better, etc. counterpart.

[chanlon]

Thanks for the responses.

"It may very well be that the DACs in the Oppo are better sounding than the DACs in the Rotel."

Anybody out there compare the SE DAC's or standard DAC's with the Rotel 1570? Personally, the Oppo DAC's sound better to me.
Is it just the flexibility of the bass management I would be forgoing If I choose to connect the Oppo via analog through Rotel's multi-channel input? I guess I wouldn't be able to do the on-the-fly adjustments for sub vol, center channel ,etc. I don't know if Oppo has discrete IR commands for sub/c/rear channel level controls.

[srb]

Anybody out there compare the SE DAC's or standard DAC's with the Rotel 1570? Personally, the Oppo DAC's sound better to me.

Why not hook up a coaxial cable from the Oppo's digital coaxial output along with the analog output already connected to the Rotel, and you can switch back and forth between inputs on the Rotel and tell us what you hear?

Steve

[chanlon]

Why not hook up a coaxial cable from the Oppo's digital coaxial output along with the analog output already connected to the Rotel, and you can switch back and forth between inputs on the Rotel and tell us what you hear?

Steve

OK, just compared the 2. Very close indeed. Slight preference to the oppo.
Sounds a little less fatiguing when using the Oppo's D/A Converter (analog connection). However, its really close. It just seems a hair more revealing and a little less edgy on the high frequencies. But its a personal preference.
One may conclude they prefer the Rotel. Both connections sound VERY good.

Furthermore, I could discern no difference in sound between the HDMI and optical connection using the D/A converter in the Rotel. The only difference would be the longer time it takes the Rotel to snap onto the HDMI signal.

When I get another few moments, I will compare the optical output with the co-axial digital output on the Apple TV. Playing the same song using the Apple Lossless file type on the Apple TV, their is a noticeable sound difference VS the CD on the oppo with either connection to the Rotel 1570.

[srb]

When I get another few moments, I will compare the optical output with the co-axial digital output on the Apple TV.

Looking at what should be the current model Apple TV on the Apple website, it appears that the Apple TV does not have a coaxial digital audio output in addition to the optical.

It does have an HDMI output, however, which should pass the audio. I am hoping there is a difference.

Steve

[MickeyVee]

I pretty much have the same setup - Apple TV & Oppo BD-83 but both running through a PS Audio Digital Link III DAC.. coax from the Oppo & optical through the ATV.
Actually, it's so close that I really can't tell the difference. The PS Audio DL III is a much better DAC than the Oppo internals and is a very nice overall improvement. Maybe the PS Audio handles jitter much better leaving the Oppo & ATV virtually identical. Pretty sweet either way.

[maxwebster]

OK, just compared the 2. Very close indeed. Slight preference to the oppo.
Sounds a little less fatiguing when using the Oppo's D/A Converter (analog connection). However, its really close. It just seems a hair more revealing and a little less edgy on the high frequencies. But its a personal preference.
One may conclude they prefer the Rotel. Both connections sound VERY good.

Furthermore, I could discern no difference in sound between the HDMI and optical connection using the D/A converter in the Rotel. The only difference would be the longer time it takes the Rotel to snap onto the HDMI signal.

When I get another few moments, I will compare the optical output with the co-axial digital output on the Apple TV. Playing the same song using the Apple Lossless file type on the Apple TV, their is a noticeable sound difference VS the CD on the oppo with either connection to the Rotel 1570.

Thanks for the update. Can you please confirm that you are using the full BYPASS mode for the Analogue inputs?

If you are not using full bypass, then you may be still using the ROTEL DACs on top of the Oppo DACS and they would sound very close.

Thanks again

[chanlon]

Yes, full bypass mode is selected when listening to the analog connection.
I find the sound is more natural when you are using the analog input connections on the rotel. It seems a little harsher when using Rotel's for the D/A processing when comparing with the Oppo.

The Apple TV is a different matter all together. When I use the analog output on the Apple TV, it sounds plain flat. Apple TV sounds much better with a digital connection to the Rotel.