Streaming Sync issues apparently resolved by USB Connection to Roon Core

Roon Software Discussion ROCK
1

Hello Roon Community,

I don’t need Roon Support help, my issue is resolved.

However, I’m curious as to why the USB cable fixed it. I have opened numerous tech support tickets regarding this issue in the past; all to no avail. Hopefully, someone in the community can shed some light on this, as I am not tech-savvy enough to understand.

I have always had issues with my Cambridge Audio getting out of sync with the other Airplay devices in the group (2 Sonos, Apple HomePod). I have tried to adjust resync delay times to no avail. It will fix it briefly, but it will eventually get out of sync again.

I should mention that this happens only with music from the library; streaming radio stations never get out of sync.

Recently, I connected the Roon Server directly to the CXNv2 via USB and the sync issues vanished–even though the CXNv2 also shows as another device in the audio settings. I’m glad, but at a loss as to how this would fix the issue. Just curious.

Thanks in advance.

Roon Server

  • Intel NUC i7 with 16 GB RAM
  • Eternal 2-terabyte USB SSD for Library
  • NUC directly connected to Google Fiber router.

Connected Audio Devices:

  • Cambridge Audio CXN-V2 (directly connected via direct Ethernet)
  • Cambridge Audio DACMAGIC 200
  • 2 Sonos One speakers
  • 2 Apple Homepods
  • All via Airplay.
11

Hi @Jim_White1,
As requested this topic is now in Roon Software Discussion.
Regards,
Carl

13

I assume that you are using an Airplay connection to the CXNv2 rather than its Roon Ready connection since you are grouping it with other Airplay devices?

Possibly its software is more efficient in using Airplay via the direct USB connection than over the network?

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14

Yes, using the CSNv2 via AirPlay group rather than the Roon endpoint. When the USB connection is active, I no longer get the sync issues.

Thanks.

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15

Thank you.

16

@Jim_White1 It’s great that your USB connection has solved the problem.

I was curious too because I have three Airplay2 speakers that I stream to, but music stays in sync.

The CXN is not keeping music playback in sync with the timing information that Roon is sending it. The following may be reasons why:

  • Network communication failures, even though your Cambridge Audio CXN v2 is connected via ethernet (faulty hardware, cable?)
  • The CXN’s Airplay2 implementation may default to using Apple’s NTP protocol for clock/timing synchronization, but Roon currently doesn’t use it
    • Roon’s June 2024 blog entry describes their implementation of the Airplay2 protocol which suggests they avoid using NTP: “…our AirPlay 2 integration is entirely unique. We don’t thread audio through Apple’s restrictive walled sound garden. Instead, Roon talks directly to your devices while delivering all the added benefits, stability, and improved sync reliability of Apple’s updated streaming technology.”
    • I don’t see log info of Roon sending timing packets of data every 3 seconds as described in OpenAirplay’s reverse engineering documentation
  • Roon’s Airplay2 implementation directly communicates timing data to audio devices. This is what I see in my Roon server logs:
    • Trace: [airplay/clientV2] [192.168.114.157] Sending SETUP #1 (session)
      • Because there’s no public documentation on Airplay2, people have reversed engineered what they could from observation:
        • The sender [Roon] communicate generic info about the device, timing protocol, timing peers and values related to encryption: ekey, eiv and et (encryption type). timingPeerInfo and timingPeerList are needed if receiver supports PTP and the sender announces timingProtocol=PTP.
        • The receiver [Cambridge Audio CXN] sets up an event channel (TCP) and communicates the port, together with its timing info. If the receiver declares PTP time synchronization, then timingPort won’t be used. If sender and receiver use NTP instead, the receiver must open a timing channel and declare its port into timingPort.
    • Trace: [airplay/clientV2] [192.168.114.157] Sending first sync packet rtptime=100626855 synctime=100715055

Roon Tech Support is aware of the issue and teased future updates to Roon’s Airplay2 implementation:

This was a lengthy reply - kudos if you made it this far :slight_smile:

1 Like
17

Thanks for the lengthy reply, as I’m sure the answer is in there somewhere. I suspect the CXN is the culprit if it is not using the Airplay protocol Roon is sending it. The Bluesound streamer I previously had didn’t have this issue when grouped. I suppose somehow the USB cable may be delivering the missing info? I don’t know, but if I disconnect the USB, the problem starts all over again.

This does raise the question: Does Roon use the standard Apple AirPlay protocol when delivering streaming radio from services such as Radio Paradise, WXPN, etc.? The sync issues do not occur when streaming Internet radio, but only when streaming from the library (2 Tb SSD), Tidal, or Qobuz.

Thanks again for the response.

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You sir are a scholar and gentleman :wink:

With USB, there’s no noticeable delay because it’s a direct connection to the music source. People typically notice music gets out of sync in 10s of milliseconds.

Network communication has microseconds to seconds of delay. Additionally, Airplay buffers music streams to help devices play together:

    • Airplay1 uses a two second buffer
    • Airplay2 let’s each device choose how much to delay or not

Are you able to group the CXN (as a USB device) with the Sonos Ones and Homepods? I didn’t think that was possible. I have a mix of speakers with Airplay, Chromecast speakers, and Roon’s RAAT:

Screenshot 2026-03-28 at 1.09.16 PM
Screenshot 2026-03-28 at 1.09.16 PM828×1042 72.7 KB

So this raises a few questions:

With your grouped devices, Is the CXN getting music from Roon over ethernet, wifi, or USB?

Let’s assume it’s getting music over the network, otherwise Airplay grouping wouldn’t work. Has the CXN moved to a different location that improves network communication?

Btw, does putting the CXN on wifi makes things better or worse compared to Ethernet?

Have you reviewed Cambridge Audio’s CXN FAQ and does their router recommendations affect your network setup (i.e., Google Fiber router manages all devices)?

What’s the bit rate of streaming music from the internet radio stations you listen to? The answer may effect perceived audio delays between devices. For example, I saw you mention in another post, that WNCW is station you listen to. For me, it streams at 64 kbps which is approximately 22x smaller than typical 1411 kbps CD quality (16-bit, 44.1 kHz) streams from Qobuz, Tidal, and local files. Meaning that those radio station streams may reach Airplay devices fast enough that you don’t notice music getting out of sync.

Screenshot 2026-03-28 at 4.22.05 PM
Screenshot 2026-03-28 at 4.22.05 PM1920×1138 300 KB

WXPN streams at 128 kbps

Screenshot 2026-03-28 at 4.47.30 PM
Screenshot 2026-03-28 at 4.47.30 PM1142×1106 148 KB

Radio Paradise seems to let you choose the streaming bit rate you want from 24 kbps to 320 kbps