Digital output of a DAC?

[Maximus89]

I have had had this vintage redbook limited resolution DAC for a month now and never questioned what the toslink and spidf OUT of my dac would be used for. In a sterophile review, this was a quote about the OUT: "Two 24-bit digital outputs are also provided to maintain compatibility with the next generation of digital components."

 

I'm still quite confused on what it is.  
Everything goes IN to the dac which is analog out to the preamp so i can't come up with any way the dac would output it's digital signal received from a transport. Am i overthinking this? Help me out here

[Edgar]

The DC-91 has 13 digital inputs. It can be used as a source selector, so whichever of those 13 inputs you choose is passed-through to the two digital outputs. That way, if you ever get tired of the DC-91 DAC section, you can buy a new standalone DAC and use the DC-91 to select the digital data stream to send to it.

https://www.stereophile.com/content/accuphase-dp-90-cd-transport-dc-91-da-processor

[Maximus89]

2 minutes ago, Edgar said:

The DC-91 has 13 digital inputs. It can be used as a source selector, so whichever of those 13 inputs you choose is passed-through to the two digital outputs. That way, if you ever get tired of the DC-91 DAC section, you can buy a new standalone DAC and use the DC-91 to select the digital data stream to send to it.

https://www.stereophile.com/content/accuphase-dp-90-cd-transport-dc-91-da-processor

Ah so it's a worthless option basically in most cases? The DC-91 won't pass through any of it's sonic benefits to the next dac? The next dac would just have it's own multiple inputs so this would only be cool if some form of the audio signal was passing through the DC-91 improving the quality of the new DAC. 

[Edgar]

Just now, Maximus89 said:

Ah so it's a worthless option basically in most cases? The DC-91 won't pass through any of it's sonic benefits to the next dac? The next dac would just have it's own multiple inputs so this would only be cool if some form of the audio signal was passing through the DC-91 improving the quality of the new DAC. 

 

Not all standalone DACs have multiple inputs.

 

As for sonic benefits of the DC-91, if you like its sound quality then you won't be buying a new standalone DAC anyway. I didn't read the article closely, but it appeared to me that the only changes that the DC-91 can make to the digital signal are to change gain and polarity.

[Maximus89]

Just now, Edgar said:

 

Not all standalone DACs have multiple inputs.

 

As for sonic benefits of the DC-91, if you like its sound quality then you won't be buying a new standalone DAC anyway. I didn't read the article closely, but it appeared to me that the only changes that the DC-91 can make to the digital signal are to change gain and polarity.

Thanks man. I must have poor reading comprehension since i read that very review before posting and it all went over my head. I can see it if i got myself a 2nd dac for DSD, but that's usually DOP through toslink and spidf. Or let's say i got a tube dac for a different flavor that also played my high res 24/96 and 24/192 music specifically and the DC-91 offers a connection no other modern dac has - ST glass optical-which i am using. In that case, i would get the benefits of the apparently too-expensive-to-produce ST Glass Optical connection benefit with another dac despite it's being output in toslink/spidf? If i did this, the DC-91 would NOT be analog out to anything-the new dac would be analog out to a preamp, correct?

Final question. The DC-91 can technically be used direct to power amp-wouldn't it benefit the sound outputting to another dac if the volume control is the DC-91?

[Edgar]

1 hour ago, Maximus89 said:

Or let's say i got a tube dac for a different flavor that also played my high res 24/96 and 24/192 music specifically

 

Make certain that the DC-91 can handle 96 kHz or 192 kHz. Not all can.

 

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the DC-91 offers a connection no other modern dac has - ST glass optical-which i am using. In that case, i would get the benefits of the apparently too-expensive-to-produce ST Glass Optical connection benefit with another dac despite it's being output in toslink/spidf?

 

Nope. The ability to accurately send bits has never been an issue with any of the digital interfaces. The problem with Toslink is bandwidth. (At least, it used to be, many years ago. The technology has largely caught up with the problem, now that it has been identified.) The bandwidth problem translated into a clock jitter problem. So if you use ST optical in part of the signal path and Toslink in another part of the signal path, the fidelity is only as good as the weakest link.

 

Quote

If i did this, the DC-91 would NOT be analog out to anything-the new dac would be analog out to a preamp, correct?

 

Correct.

 

Of course, you could still connect the DC-91 analog output to a different preamp input, if you wanted to choose your flavors according to your mood.

 

Quote

The DC-91 can technically be used direct to power amp-wouldn't it benefit the sound outputting to another dac if the volume control is the DC-91?

 

Hard to say. For a long time, analog volume control performed better than digital volume control. That has changed as DACs have improved.

[Maximus89]

Appreciate it! Well this dac is 30 years old and sounds better than 2 different Audio Note Dacs, a modwright tube modded oppo and an ares ii and several other $1k range dacs i had in here. I was expecting an r2r ladder dac type of sound like the Ares II which i found addictive, but it's a very clean modern sound. Crazy revealing, but a bit lean on the mid bass it's only drawback and bad recordings sound bad unlike through a NOS ladder dac where everything sounds analog and lush imo. They retain their value so i'll likely try a dsd capable NOS r2r DAC next or decide to send it to a tech to recap and modify it-here's a quote containing some of what he'd do

"I certainly agree with you on the sound of a stock or "conventionally upgraded" Accuphase DC-91. For god knows what reason, other than it was common practice at the time, each of the 32 pcm63 chips has it's own feedback i/v opamp, then into a common buffer, then into a HORRIBLE GIC filter, then output buffer and balanced driver amp. With single common passive i/v resistor per 16 dacs per channel, then my no-feedback voltage gain + line driver stages, plus way larger caps around each of the dacs(over 500 nice Nichicon caps I had to replace with larger nice Nichicon caps, exhausting), the resulting sound is absolutely spectacular, without even changing the ancient YM3436 input receiver or d/f arrangement."

[Edgar]

8 hours ago, Maximus89 said:

the ancient YM3436 input receiver

 

I'm pretty sure that the YM3436 cannot handle 96 kHz or 192 kHz.

[Maximus89]

 
I'm pretty sure that the YM3436 cannot handle 96 kHz or 192 kHz.

No need for high resolution. I mentioned that before I knew what the output meant- thinking i could send the signal out to another dac which would do high res while having the signal pass through the dc-91. Im good with Redbook. Theres good measuring cheap delta sigma dsd dacs if I want a 2nd dsd dac. Or rather 3rd as I have a multichannel hdmi dac as well.

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