Toslink problem with new dac.

[audiobliss]

I have been using toslink for weeks now with no problem going into the dac in my McIntosh C47. Yesterday I took delivery of a MDA200 dac.
Hooked it up this morning and the toslink output from the Pro is distorted.
I tried three different cables, same thing. Toslink input from my TV is fine.
Coax from the Pro to the new dac is fine. I checked all the settings but nothing helped. I have rebooted the Pro and the dac a couple times.
Any idea what's going on, it just makes no sense that it was fine with one dac and distorted with the new one.

 

[Brantome]

Did you go thru the audio output resolution tests again with the new DAC? For arguments sake, maybe the new DAC’s toslink input has issues with 24/192 where the first one didn’t? Your tv is likely to be 24/48 so perhaps it doesn’t trigger the issue…

 

[audiobliss]

I lowered the resolution to 96, but it didn't help.

 

[audiobliss]

Just hooked up my ifi bluetooth outputting Ldac with optical and it plays perfectly.
So definitely something with the Pro optical output..

 

[onlyoneme]

The same cable as before also doesn't work? Both toslink inputs are affected? What do you mean exactly by "distorted"?

 

[audiobliss]

Yes, both inputs on the dac , same result. Distorted, sounds like a bad connection, or like the music is blured.

 

[onlyoneme]

Did you play with Digital Gain setting on the DAC, any differences? Did you try to lower WiiM's output extremally, to 44.1/16?
Apart of that the behavior looks like very bad jitter rejection if ports and cables are not faulty.

 

[audiobliss]

Yes, I set the digital gain in the dac to the same for optical and coax. I didn't lower the wiim to 44, I only tried 96. I will try 44 later.
I think the the wiim is putting out some bad optical that the dac doesn't like. I think I will take it to another system and try it with the c47 again.

But right now, my ifi zen blue is sounding so good with the new dac, I my just keep it here in this system. It may not be bit perfect, but it's pretty close, with zero issues ever.
No waking it up, no restarting the app, just hit play every time.

 

[audiobliss]

Did you play with Digital Gain setting on the DAC, any differences? Did you try to lower WiiM's output extremally, to 44.1/16?
Apart of that the behavior looks like very bad jitter rejection if ports and cables are not faulty.

Found the problem. When you mentioned the digital gain settings, it had me thinking about it.
While going through the setup for the dac, I had set the gains to +15db max, but I had no idea it could affect anything other than volume.
I went back and looked more in the manual and saw were it said , default was +15 for hdmi, and 0 for optical. That made me think, hmmm, why would they set optical at 0.
So I said, well let me put it back at 0, and see what happens.

Well , that did it . It seems the Pro puts out so much gain from the optical, that it must overload the dac. I am sure someone can give us a mire technical explanation.
It must put out way more that my other sources.

 

[Mr Ee]

I'm sure you can do some internet searching on why too much gain can cause distortion!
Glad you got it sorted.

 

[audiobliss]

Never had a dac with adjustable digital gain before, I guess the more you pay , the more you get.

 

[onlyoneme]

Found the problem. When you mentioned the digital gain settings, it had me thinking about it.
While going through the setup for the dac, I had set the gains to +15db max, but I had no idea it could affect anything other than volume.
I went back and looked more in the manual and saw were it said , default was +15 for hdmi, and 0 for optical. That made me think, hmmm, why would they set optical at 0.
So I said, well let me put it back at 0, and see what happens.

Well , that did it . It seems the Pro puts out so much gain from the optical, that it must overload the dac. I am sure someone can give us a mire technical explanation.
It must put out way more that my other sources.

Pro doesn't add any gain itself if volume is fixed and EQ is off, but +15dB gain on the DAC is a lot. It will clip all the time giving you a huge amount of distortions.
Using this gain for any bit-perfect source is a bad idea.

 

[audiobliss]

Thanks for input that made me realize the issue. I never would have suspected the gain setting, especially since the coax worked fine with the same setting.
Coax must be much less sensitive to gain settings than hdmi and optical.

Glad we figured it out just in time, I thought the Pro was broken. I have two days left in my return window, I was almost ready to pack it up.

 

[onlyoneme]

The gain setting seems to work only for hdmi and toslink inputs, according to the manual. Coax input is not affected at all.

 

[audiobliss]

Yes, that's where I saw the default was 0db for optical, so I reset it to 0.
I think I am going to start using coax, I was never a fan of those connectors on the toslink cable anyway.

 

[Mr Ee]

Yes, that's where I saw the default was 0db for optical, so I reset it to 0.
I think I am going to start using coax, I was never a fan of those connectors on the toslink cable anyway.

When you wrote "Coax from the Pro to the new dac is fine." in your original post, I was going to write "There's your solution then!", but assumed you had a reason for wanting / needing to use the optical output of wiim

 

[audiobliss]

I have always favored optical, although I really hate fiddling with its connector, mainly because the supposedly galvanic isolation. But I really don't hear much sound difference between the two.
So I just dug up a nice old Monster cable digital coax I had in the closet. Luckily to my surprise the barrel fits nicely in the Pro. It sounds great, and maybe it allows the Pro to bleed off some of its nasties, who knows.