Are all asynchronous USB inputs similar?

Ethernet is the best possible option. We will all migrate to it eventually. It has the same benefits as Async USB, but avoids the issues that occur in computer software, making the computer/ipad a "don't-care".

I don't expect Ethernet to improve sound quality significantly over good USB interfaces, but computer optimization will hopefully not be necessary anymore, which is a big win for audiophiles.

Steve N.
Empirical Audio

FWIW, assuming comparably good implementation of the various possible approaches IMO the most ideal one would be a **reliably functioning** wifi link, with the computer (and the digital and switching noise it generates) located nowhere near the audio system, and powered from a different AC branch.

Wired ethernet would be my next choice (with the computer powered from the same AC branch as the system, to avoid possible ground loop issues).

The following paragraph from this paper by Steve elaborates, persuasively IMO:

Networked audio (Ethernet), both wired and WiFi is a unique case. Because the data is transmitted in packets with flow-control, re-try for errors and buffering at the end-point device, it is not as much of a real-time transfer as USB, S/PDIF or Firewire. The computer transmitting the data packets must still keep-up" the pace to prevent dropouts from occurring, but the real-time nature of the transfer is looser. Unlike with other protocols, there can be dead-times when no data is being transferred. Networking also avoids the use of the audio stack of the computer audio system since it treats all data essentially the same. This avoids kmixer on XP systems and the audio stacks on Mac and PC Vista. Because of the packet-transfer protocol of Ethernet and data buffering at the end-point, the jitter of the clock in the computer is a non-issue. The only clock that is important is the one in the end-point device. Examples of end-point devices are: Squeezebox, Duet and Sonos. This would seem to be the ideal situation, which it certainly is. The only problem that can occur is overloading the network with traffic or WiFi interference, which may cause occasional dropouts. The problem for audiophiles is that the majority of these end-point devices were designed with high-volume manufacturing and low-cost as requirements, with performance taking a lower priority. As a result, the jitter from these devices is higher than it could be. It should be the lowest of all the audio source devices available.

Regarding USB, I have no relevant experience, but my perception has been that a lot of Audiogon members utilize asynchronous USB DACs with results that are satisfactory to them, while only one member consistently criticizes it. FWIW.

Regards,
-- Al

The USB audio interface dominates the audiophile world because the USB interface dominates the computer world. Whether or not it's the best interface is somewhat irrelevant since as a practical matter for most it's all there is. We should be thankful that it works as well as it does.

BTW, I use firewire and a dedicated soundcard in my systems. I was an early adapter of wireless and found it not very reliable.

Onhwy61,
The USB dominance is not debatable and the Baetis Audio designer openly concedes this fact. His position is it not the best sounding and he simply offers an alternative he believes is superior in sound quality. That's it really, he doesn't deny that many enjoy USB linked systems.
Charles,

In order to make broad conclusions about USB IMO, they must have auditioned every USB interface with every server configuration. This is highly unlikely. They can only rely on their own experience, just like the rest of us.

There are a lot of poorly conceived USB interfaces, even big names. Most of them on popular DACs are not that great. This is the reason why some people have a less than stellar experience with USB.

If you ask Antipodes, whose server is excellent, they would likely make the opposite claim, that with the RIGHT USB interface, USB is far superior to S/PDIF.

I, on the other hand have had a LOT of experience with many different high-end PCI cards, Sonos, Squeezebox2, 3, Duet, Touch, Firewire interfaces and several USB interfaces, adaptive and Async. I have designed or modded all of the above. My USB interface is 5th generation (Off-Ramp 5) and 6th is in prototype stage. I have used or modded servers including Naim, Qsonix, Soolos and Antipodes as well as modified Macs and PCs. I believe I am in a better position to determine which technology is superior. Empirical Audio has been in business for 18 years and I have been doing digital design for 38 years. Async USB driving S/PDIF or I2S can be every bit as good if not better than PCI bus driving S/PDIF, providing a good design and implementation. Driving I2S it should be better because it avoids S/PDIF conversions.

Steve N.
Empirical Audio