It's completely DAC dependent IMHO! Some DAC's like my Holo Audio May KTE have done an excellent job of implementing the USB and it has double galvanic isolation. USB has come a long way and can sound excellent!
Streamer output options
In my younger days, I was told so often that spdif was better than usb that it became doctrine. I'm in the market for a 2k$ish streamer and I see many higher end streamers with usb outputs that pass far higher res data than the spdif 192/24 does. My DAC takes either, but not i2s. Are the new implementations of usb now better than spdif?
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@mclinnguy Thank you for the Laugh of the Day. Although I'm sure there are many here who don't get the joke. 🙄 |
@mclinnguy OK Will do. And while I'm at it I'll ask about this, too: "At each end of the cable you can see a pair of “speaker kegs”. These are similar to the kegs we use on our powercords. However they are quite different – the power cords kegs are designed to pass 50/60Hz but the speaker kegs must pass the whole audio band. So these kegs are reformulated and tuned to this application." Kegs are a slang term for ferrite beads, often found used legitimately for damping RF on power cables. No problem, That has a measurable impact as a low pass filter. And they are inexpensive - You can get an 80pc assortment on Amazon for $20.99. So, lots of opportunity to reformulate and tune for the price of a pizza. But they are a low pass filter, so they have other measurable impacts when used on signal cables, like hysteresis and latency, as well as limiting bandwidth. All immaterial on power cables, not so immaterial when dealing with signals. |
@panzrwagn If you are looking for an explanation feel free to ask the source of that information and the designer of those cables. I don't even use a USB cable. Let me know how it goes. https://www.madscientist-audio.com/
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@mclinnguy "noise that piggybacks on the data itself" Somebody is going to have to explain that one to me. USB-Audio uses isochronous, interrupt, and control transfer. Characteristics of the Interrupt Transfer mode are:
USB has error control and management. Any 'noise that piggybacks on the data' to be relevant (audible) would have to modify and corrupt the bitstream. That would cause a checksum error and have the effect of triggering the error correction. Then, a retransmit would occur of uncorrupted data. The concept of 'noise that piggybacks on the data' causing audible issues is not possible with USB data and simply not applicable. Anything and everything you hear from a streaming source is derived from the bitstream. RF noise, at frequencies thousands of times higher than human hearing is taken care of by the reconstruction filter of the DAC. Any audio band noise measurable after that point on is from the analog section of the DAC, downstream line amp, or power amp, and likely due to improper gain staging. |
If you’re running usb out of a computer there’s a possibility that power might be running through also and that can add a bunch of noise, but if you’re running out of a streamer that’s set up for using usb as it’s preferred output like Aurender, the signal will be a lot cleaner before it hits the DAC. |
Implementation of interfaces needs to be taken on a case by case basis. How can anyone state categorically any single interface is the best. Usb optimization varies greatly across both streamers and dacs. I2S not offered on a great number of streamers so DDC's employed, optimization of this output varies with these, for dacs since this native signal path, less variability here except with quality of internal clock.
One would have to actually optimize and implement these interfaces in their own setups to determine superiority. I've tried any number of usb optimizations over the years, this with variety of streamers and dacs, with present setup I2S provides superior sound quality vs usb, this with both my Musetec DH-DA006 (sabre chip) and Laiv Harmony (R2R). Musetec has one of the most sophisticated usb boards I've seen, Laiv middle of road. |
Per one cable manufacturer regarding history of digital cables: Before USB, there was Coaxial (S/PDIF) digital. This suffers from the technical problem that the clock must be recovered from the data stream, a technique that produces more jitter than desirable. Then came asynchronous USB, where the DAC controls the data rate, so a high-quality, low-jitter clock can be used in the DAC. This was technically a better solution, and it should sound perfect. But it didn’t. In fact, it sounded worse than using a Coaxial cable connection. Some blamed noise on the 5V line. Others blamed noise on the ground line. Various techniques were used (in an effort to offset the sound degradation), in the form of add-on boxes and dongles; galvanic isolation, regeneration, and noise filtering. These often gave some improvement but at a high cost; they also often left their own footprints on the music. So, in 2018, we designed the original Black Magic USB cable. We found the real problem is not noise on the ground or 5V lines—it’s noise that piggybacks on the data itself. Black Magic uses innovative techniques to reduce and absorb this noise, as well as special measures to prevent its radiation from the cable. In 2022, we revised the whole cable, producing the USB ULTRA cable. This performs at an entirely new level from the original. In 2023, we pulled out all the stops and produced the USB GOLD version. This uses selected silver/gold wire and a different kind of mechanical damping. And in 2024, we have a new design: Prime – our best yet. |
I'll reword your question a bit:
Yes- In the case of my streamer manufacturer. According to Antipodes there was no USB driver option available that was as good as AES. It was only last year they achieved a USB strategy that equalled the sound quality of the other digital outputs and now they state the AES and USB outputs are more or less equal in sound quality. (clock considerations aside) They offered upgrades to existing owners to update their units to the new hardware, as well as other updates, which is fantastic from a customer standpoint, but I have yet to do that- I am happy with my AES at the moment even though as others have stated it is limited to non-DSD 192/24 resolutions. All my Native DSD files are sitting dormant. It is worth pointing out there are many excellent servers that do not have AES and use USB only- Melco, XACT, Aurender... |
There were a couple of issues with early USB. It was not asynchronous, and early implementations of asynch were not universal. In addition, still recently, DAC vendors don’t always ensure the USB interface is galvanically isolated, which can cause digital and/or analog ground loops. The former increases jitter significantly, the latter adds hum. Especially bad when coming from a PC. S/PDIF, while lower bandwidth, over optical suffered none of these issues. Today USB is asynchronous and the highest possible bandwidth. Get an inexpensive USB isolator and you are good to go. Another thing that’s happened relatively recently is that the clocks in DAC’s have gotten amazingly good (and cheap) compared to pre-2000 days. This means that the highest possible resolution of a clock is next to the DAC and therefore it should be in charge of the timing from upstream, which is what happens with USB asynchronous. BTW, Ethernet is galvanically isolated by design, but not noise isolated due to coupling caps that may occur around transformer windings. |
I2S was pushed by those selling I2S. Trashing USB was a necessary part of this marketing campaign. I have an Innuos that is optimized for USB. I have a Grimm that is optimized for AES/EBU. I like the AES because it is a great connector and there are a lot of good cables available. However, there are now great cables available for USB. Bottom line, don’t buy a DAC or a Streamer just for I/O options. Use the option that the OEM recommends as they have implemented that option best. Beware of I2S as there is no standard for implemetation. So your DAC may do it one way and your streamer another. Jerry PS both options have been better than SPDIF in my experience, but SPDIF is better than optical. |
Agree that it depends on the manufacturer and how they design their equipment. My Innuos Zen Mk3 streamer has a USB output to my Holo Audio Cyan 2 and it sounds great. Got it used for under $2K from an excellent local dealer. I got a short cable that was just the right length from Pine Tree Audio made in good old Massachusetts. BTW I buy local whenever I can. Support your local dealers if you can before there’s nothing left but online options. |
There are some very good low-priced I2S/SPDIF streamers that have extremely good specs, like the Holo Red and the Mercury V3. I use the Mercury, which is only $500 and far surpasses the USB output of my Mac Mini server in terms of accuracy and cleanliness. But I don't do extreme upsampling or DSD. OTOH a friend of mine (who has what I consider a reference system) prefers USB and has a custom-built streamer with JCat USB and network cards. If he weren't happy with it I would hear about it. ;-) I think in the end it depends on what level of playback you want and if the higher resolution options are worth it to you. It seems like you need to spend a bit more to get high-quality USB output, but that shouldn't stop you from going that route. Relatively affordable USB streamers from SOtM and Sonore are very popular and have good reputations. Then there's Lumin, Aurender and others that seem to be very satisfactory in terms of USB quality. At that point, you need to look at the connection interfaces, which vary in ease and quality. There are a number of threads here about that. |
Im my experience DAC designers make choices to best meet their objectives. And there is no definitive answer as to which input will sound best on a given DAC. It seems to be case by case. Some are optimized for one input, others try and make them all sound the same. And modern implementations of USB can be excellent, when the designer makes it so. Read the reviews of your DAC and read between the line to determine if your DAC is optimized for USB. |