Why use USB from streamer to DAC?

[popej]

resampling artifacts are obvious

Infamous resampling by Creative
Actually this card already solved the main problem, which was enormous IMD distortion. 48kHz is only a bit cleaner:

RightMark Audio Analyzer test : [DirectSound] SB Audigy 2 Audio [A400]

 

[TonyJZX]

i think at this point we see that coax and toslink are legacy formats

going forward its going to be type-c and hdmi

conventional sp/dif i think didnt go past ac3/dts 5.1?

i think to get atmos 7.2 you need hdmi (I own an atmos 7.2 receiver but i kind of dont care that much about surround any more)

and its not on some blu ray players given it will not suffice for the full BR experience

one way you can tell that coax and toslink is going out of fashion is that the single coax cables and toslink fibre cables are cheap as hell given people dont want that stuff any more?

i mean even in my case i dont think I've owned more than half a dozen peices of optical cable

 

[formdissolve]

i think at this point we see that coax and toslink are legacy formats

going forward its going to be type-c and hdmi

conventional sp/dif i think didnt go past ac3/dts 5.1?

i think to get atmos 7.2 you need hdmi (I own an atmos 7.2 receiver but i kind of dont care that much about surround any more)

and its not on some blu ray players given it will not suffice for the full BR experience

one way you can tell that coax and toslink is going out of fashion is that the single coax cables and toslink fibre cables are cheap as hell given people dont want that stuff any more?

i mean even in my case i dont think I've owned more than half a dozen peices of optical cable

Optical isn't going anywhere. Millions of cheap sound bars are sold that have optical because cheap TVs don't have ARC out.

Plus, although less common, the ADAT standard uses optical which some still use in the pro audio space.

SPDIF will be used a long time, and will be standard on most DACs for years to come (for good reason).

 

[MaxwellsEq]

Can anybody explain to me what the obsession is with people only wanting to use a USB connection from their streaming device to their DAC? This seems very prevalent in the PS audio forums, like coax or optical is just not up to transferring bits correctly so must have USB for anything to work correctly.

Higher bitrates are not defined in S/PDIF and Toslink, so are not guaranteed to work. Complex formats are also undefined.

 

[tmtomh]

I have noticed one "user-interface"/usability difference between USB on the one hand and SPDIF/TOSLINK on the other, with every combination of gear I've ever used. The difference affects how the gear behaves when I stop playing music for more than, say, a minute or two, and then hit Play again on my streamer/digital source.

• USB: Music resumes, immediately at the set volume, with zero delay (or perhaps a very short delay of less than one second).
• SPDIF/TOSLINK: Music takes 2-3 seconds to resume, and when it does so it fades in - quickly, just a second or so, but still definitely a fade-in.

Honestly I'm ambivalent about this. For when I first start a listening session, or when I resume playback from the beginning of a song or album, I prefer the USB behavior because I don't like losing the first couple of seconds of a track to the signal reacquisition process and fade-in with SPDIF/TOSLINK.

But if I pause in the middle of a track and then want to resume a little later, I prefer the SPDIF/TOSLINK behavior, because it's much less jarring than the USB behavior when resuming midway through a piece of music.

I would be curious to know if anyone has experienced different SPDIF/TOSLINK behavior than this. As I note, I've seen this no matter the gear I've used - but I've only tried 3-4 streaming/digital-source devices and a couple DAC/receiving devices, so maybe it's just the models I've used?

 

[Greenman]

I have noticed one "user-interface"/usability difference between USB on the one hand and SPDIF/TOSLINK on the other, with every combination of gear I've ever used. The difference affects how the gear behaves when I stop playing music for more than, say, a minute or two, and then hit Play again on my streamer/digital source.

• USB: Music resumes, immediately at the set volume, with zero delay (or perhaps a very short delay of less than one second).
• SPDIF/TOSLINK: Music takes 2-3 seconds to resume, and when it does so it fades in - quickly, just a second or so, but still definitely a fade-in.

Honestly I'm ambivalent about this. For when I first start a listening session, or when I resume playback from the beginning of a song or album, I prefer the USB behavior because I don't like losing the first couple of seconds of a track to the signal reacquisition process and fade-in with SPDIF/TOSLINK.

But if I pause in the middle of a track and then want to resume a little later, I prefer the SPDIF/TOSLINK behavior, because it's much less jarring than the USB behavior when resuming midway through a piece of music.

I would be curious to know if anyone has experienced different SPDIF/TOSLINK behavior than this. As I note, I've seen this no matter the gear I've used - but I've only tried 3-4 streaming/digital-source devices and a couple DAC/receiving devices, so maybe it's just the models I've used?

I don’t get this behaviour streming from WiiM Mini over optical to smsl su1, Gustard X26pro or Gustard r26. Restart on pause is near instant (maybe 0.5 seconds).

I can only assume that your dac is buffering the input to try to reduce jitter (as per post 18) on optical but not on USB.

 

[tmtomh]

I don’t get this behaviour streming from WiiM Mini over optical to smsl su1, Gustard X26pro or Gustard r26. Restart on pause is near instant (maybe 0.5 seconds).

I can only assume that your dac is buffering the input to try to reduce jitter (as per post 18) on optical but not on USB.

Thanks! Quick question: when you say possible 0.5 second pause on restart, does 0.5s of the music get cut off as a result, or is it literally just a delay and the music starts at the very beginning of the track?

Just as an FYI, here are the combinations of gear where I've experienced this:

• Mac mini --> Oppo UDP-205
• Mac mini --> MiniDSP SHD
• Sony UBPX800 --> Oppo UDP-205
• Sony UBPX800mk2 --> MiniDSP SHD
• Sony UBPX800mk2 --> SPDIF/TOSLINK digital switch --> Genelec 8351b digital input
• Mac Mini --> SPDIF/TOSLINK digital switch --> Genelec 8351b digital input

In all cases, I get a short delay/very-short fade-in, with 1-2 seconds of the music affected, when resuming over SPDIF/TOSLINK, and near-instantaneous, non-faded-in when resuming over USB (in the above chains where USB is an option).

My initial assumption would be that it's a high-jitter signal from SPDIF/TOSLINK, or a quirky design of the receiving device. But the number of devices and different combos of devices I've experienced this with makes me question that assumption.

Of course, what I'd love is a device that gave me SPDIF and USB input (for my disc player and Mac mini, respectively), with SPDIF or AES output (to go to the Genelecs). But I haven't been able to find such a device unless I'm willing to pay $500 or more. That's more than I'm willing to pay just to get rid of this small delay/fade-in issue.

 

[Greenman]

Thanks! Quick question: when you say possible 0.5 second pause on restart, does 0.5s of the music get cut off as a result, or is it literally just a delay and the music starts at the very beginning of the track?

Humm, well it may just miss a very small period of music, but I’ve had to listen about a dozen time to convince myself if it’s chopping any out or not, it may miss about 0.25 seconds of music, with about a 0.25 second fade in, certainly nothing of the order of 1-2 seconds.

Having said all that, I’m not sure your issue would concern me hugely. How often do you actually pause mid track? Ok occasionally to take a phone call or something, but it’s not like I’m pausing 10 times every half hour or something!?

 

[MaxwellsEq]

SPDIF/TOSLINK: Music takes 2-3 seconds to resume, and when it does so it fades in - quickly, just a second or so, but still definitely a fade-in.

I've not experienced that. Something in your configuration?

 

[tmtomh]

Humm, well it may just miss a very small period of music, but I’ve had to listen about a dozen time to convince myself if it’s chopping any out or not, it may miss about 0.25 seconds of music, with about a 0.25 second fade in, certainly nothing of the order of 1-2 seconds.

Having said all that, I’m not sure your issue would concern me hugely. How often do you actually pause mid track? Ok occasionally to take a phone call or something, but it’s not like I’m pausing 10 times every half hour or something!?

Thanks! And I agree RE mid-track - the issue (albeit a very minor one I agree) is not with that, since I actually prefer the quick fade-in behavior of SPDIF/TOSLINK in that scenario.

Where I find it a bit annoying is when I first start a new music listening session. The first time I press Play (I use the Apple Music app running on the Mac mini), playback starts, and then around the 0:02 mark the music fades in. Same thing if I instead play a CD with my disc transport. If there's less than a second or two of silence at the beginning of the first track, then a little music gets cut off, and whatever the first sound is, it's subject to that (admittedly quick) fade-in. Same for if I finish listening to an album, then don't play another album within a couple of minutes (or whatever precise time interval is required for the connection to have to re-acquire the next time I press Play). So when I start a new album, same thing happens.

Per @MaxwellsEq 's comment above, it could be my gear or configuration - in fact I'd love if it were my configuration because they I could remedy it. But I've experienced the same thing with different gear and different inputs, as listed in my prior comment.

So for example, a few years ago I tried a Sony UBP-X800 disc player feeding my Oppo UDP-205 via the Oppo's SPDIF or TOSLINK input (I forget which). I had this issue. Then earlier this year when I got my Genelec 8351s, I no longer needed the Oppo's built-in DAC functionality, so I connected its SPDIF output to the Genelecs' AES EBU input. The problem there was that I could no longer get sound from my Mac mini music server. The reason was that it was connected to the Oppo's async USB input, and that input on the Oppo is wired directly to the analogue outputs. So I had to switch to the mini's optical output feeding the Oppo's optical input. Sound was restored - but unlike when they were connected via USB, I had the same issue with this small latency and fade-in, and 1-2 seconds of cut-off music.

Recently, based on someone recommending it in a thread here at ASR, I got this digital switch:

Automatic SPDIF (Optical/RCA) Audio Switch by Beni_Skate on Tindie

Automatic Optical/RCA SPDIF Audio Switch with Optical/RCA SPDIF Output and additional high quality Audio DAC

www.tindie.com

It works great and really simplifies my setup, but it has no USB input, so my disc transport goes to an SPDIF input on the switcher and the Mac mini goes to a TOSLINK input. Same deal - small delay and quick fade-in.

So if it's the DAC inside the Genelecs, then why did the same thing happen when the Oppo was serving as my DAC? And if it's the Mac mini's optical output, then why does the same thing happen with my disc transport? And if it's the digital switcher, then why does it happen when I use a MiniDSP SHD as a digital switcher?

You get the idea: for each link in the chain, I've used 2-3 different pieces of gear, and no matter what gear or in what combination, I get this behavior when SPDIF or TOSLINK is the connection method, and I don't get this behavior when USB is available as a connection option.

 

[onlyoneme]

Thanks! And I agree RE mid-track - the issue (albeit a very minor one I agree) is not with that, since I actually prefer the quick fade-in behavior of SPDIF/TOSLINK in that scenario.

Where I find it a bit annoying is when I first start a new music listening session. The first time I press Play (I use the Apple Music app running on the Mac mini), playback starts, and then around the 0:02 mark the music fades in. Same thing if I instead play a CD with my disc transport. If there's less than a second or two of silence at the beginning of the first track, then a little music gets cut off, and whatever the first sound is, it's subject to that (admittedly quick) fade-in. Same for if I finish listening to an album, then don't play another album within a couple of minutes (or whatever precise time interval is required for the connection to have to re-acquire the next time I press Play). So when I start a new album, same thing happens.

Per @MaxwellsEq 's comment above, it could be my gear or configuration - in fact I'd love if it were my configuration because they I could remedy it. But I've experienced the same thing with different gear and different inputs, as listed in my prior comment.

So for example, a few years ago I tried a Sony UBP-X800 disc player feeding my Oppo UDP-205 via the Oppo's SPDIF or TOSLINK input (I forget which). I had this issue. Then earlier this year when I got my Genelec 8351s, I no longer needed the Oppo's built-in DAC functionality, so I connected its SPDIF output to the Genelecs' AES EBU input. The problem there was that I could no longer get sound from my Mac mini music server. The reason was that it was connected to the Oppo's async USB input, and that input on the Oppo is wired directly to the analogue outputs. So I had to switch to the mini's optical output feeding the Oppo's optical input. Sound was restored - but unlike when they were connected via USB, I had the same issue with this small latency and fade-in, and 1-2 seconds of cut-off music.

Recently, based on someone recommending it in a thread here at ASR, I got this digital switch:

Automatic SPDIF (Optical/RCA) Audio Switch by Beni_Skate on Tindie

Automatic Optical/RCA SPDIF Audio Switch with Optical/RCA SPDIF Output and additional high quality Audio DAC

www.tindie.com

It works great and really simplifies my setup, but it has no USB input, so my disc transport goes to an SPDIF input on the switcher and the Mac mini goes to a TOSLINK input. Same deal - small delay and quick fade-in.

So if it's the DAC inside the Genelecs, then why did the same thing happen when the Oppo was serving as my DAC? And if it's the Mac mini's optical output, then why does the same thing happen with my disc transport? And if it's the digital switcher, then why does it happen when I use a MiniDSP SHD as a digital switcher?

You get the idea: for each link in the chain, I've used 2-3 different pieces of gear, and no matter what gear or in what combination, I get this behavior when SPDIF or TOSLINK is the connection method, and I don't get this behavior when USB is available as a connection option.

Turn off standby mode on the output of your switch - set it to always on. Maybe it will help with this scenario.

 

[tmtomh]

Turn off standby mode on the output of your switch - set it to always on. Maybe it will help with this scenario.

Thanks! The switch is very simple and I don't think it has standby mode (or if it does, then it has no switch to disable it). And again, my Oppo UDP-205 did the same thing.

 

[CtheArgie]

To be clear, McGowan is AGAINST using USB. His recently launched streamer, the AirLens, has NO USB connection option. Purposely.

‍

 

[onlyoneme]

Thanks! The switch is very simple and I don't think it has standby mode (or if it does, then it has no switch to disable it). And again, my Oppo UDP-205 did the same thing.

You can do that programmatically over its usb port. Details are in the manual, including the link to the tool.

 

[chelgrian]

Optical isn't going anywhere. Millions of cheap sound bars are sold that have optical because cheap TVs don't have ARC out.

Plus, although less common, the ADAT standard uses optical which some still use in the pro audio space.

SPDIF will be used a long time, and will be standard on most DACs for years to come (for good reason).

The professional world has largely moved to Audio over IP. There is still AES3 in use largely because it's drastically cheaper to implement than any Audio over IP. As you say similar things apply for SMUX over optical. Finally there is still a lot of MADI in broadcast and some pockets of live sound.

None of these formats are going anywhere because they have particular properties in terms of channel count or ability to run over existing cabling or over specific distances.

If you were starting from scratch then USB would be an over complicated and expensive way to make audio connections. However since most streamers are based on commercially available single board computers the designers of those have already sunk the cost of the USB design and amortized it over many market segments.

Similarly there are off the shelf USB to i2c components available because the development cost has already been sunk creating audio interfaces by various companies. It's thus extremely cheap to add USB in to a DAC using an off the shelf XMOS chip.

 

[tmtomh]

You can do that programmatically over its usb port. Details are in the manual, including the link to the tool.

Oh, thanks! It looks like the client tool is Windows-only, and I don't think I have any Windows machines currently, but maybe I can figure something out. It looks like the only command that would disable standby would be the "Keep all outputs always on" command - yes?

 

[tmtomh]

To be clear, McGowan is AGAINST using USB. His recently launched streamer, the AirLens, has NO USB connection option. Purposely.

‍

I assume McGowan is against USB because it's not galvanically isolated.

 

[TonyJZX]

I assume McGowan is against USB because it's not galvanically isolated.

I think Paul is one of those folks who sees something new and really doesnt want to delve into how it works or why its good and only sees its 'faults' real or imagined and then asks "experts" online to prove his theory... that usb is 'problematic'.

A 'problem' exists... he cant prove it exists but he sells something that supposedly 'fixes' it and he hopes 'smarter' people will chime in on this chats... "that would be great".

 

[onlyoneme]

Oh, thanks! It looks like the client tool is Windows-only, and I don't think I have any Windows machines currently, but maybe I can figure something out. It looks like the only command that would disable standby would be the "Keep all outputs always on" command - yes?

Yes. And there are serial commands provided to be sent over usb port, the attached tool is not required.

 

[dualazmak]

and it will handle multiple channels.

Yes, really important pros of USB routing. Even through USB 2.0 (not USB 3.0), I actually enjoy 8-Ch Out plus 8-Ch In, up to 192 kHz 24 bit, to/from OKTO DAC8PRO via its dedicated USB ASIO driver.

I also have my own "historic" and "practical" background/reasons for sticking to "All-in-USB-ASIO routing" partly due to safety concerns (ref. here).