Roon server 2.66 compatibility issues with KEF LS50 and LSX (ref#A6H8NQ)

Support
1

Hi! What’s not quite right with Roon?

· None of the above quite fits

None of the above quite fits

· None of these quite match

Tell us what's going on

· Roon server version 2.66. Kef LS50 Wireless II firmware 4.1 and Kef LSX II firmware 3.0. Kef speakers no longer play DSD or MQA files, playback stutters and / or crashes the speaker (can’t activate the end point). LS50 II can play DSD 64 but not above, LSX can no longer handle DSD at all (despite both speakers being able to do so via Room for years). MQA files break up and sound awful on playing, if they play. Changing render / decoder settings briefly helps but not foolproof. Both speakers can play these files successfully direct, outside of Roon, via the Kef Connect app. No issues with the same files / playback on my non-Kef devices (raspberry pi endpoint).

Tell us about your home network

· ASUS RT-BE92U, Tp-Link powerline adaptors, no VPN, 300mb fibre broadband.

2

Hey @Chris_Gosling,

Thanks for writing in and for sharing your report! From a fresh Roon Server diagnostic report, we can see that the LSX II in particular drops to standby repeatedly mid-track, seconds after playback begins, regardless of format (FLAC, MQA, DSD). This is happening on both speakers but is far more frequent on the LSX II. This is the primary cause of the crashes and inability to activate the endpoint, Roon starts playing, the speaker reports back status: Lost, reason: standby, and the endpoint goes dead.

Based on this, and a few other reports from Kef releated issues, I believe this is a firmware bug in the new KEF firmware. The speakers are entering standby erroneously while Roon is actively streaming. The KEF Connect app bypasses Roon’s RAAT protocol entirely and uses the speaker’s own internal playback path, which is why it works fine there.

We’re also seeing that both speakers are internally downconverting everything.

Both speakers still advertise full DSD support (DSD64/DSD128/DSD256) to Roon, so Roon tries to send DSD natively. However the signal path logged shows what actually happens:

{"type":"dsd_to_pcm","from_sample_rate":11289600,"to_sample_rate":192000,"quality":"none"}

Every single DSD setup request whether DSD64, DSD128, or DSD256 results in the speaker internally converting DSD to PCM (192kHz for LS50 II, 96kHz for LSX II). The quality: “none” flag means this is lossy/degraded conversion happening inside the speaker firmware, not the hi-res native DSD path you’d want.

This is new behaviour also seems to be introduced by the recent firmware updates. Previously, these speakers passed DSD natively; now they’re forcibly converting it on their end.

As a next step, if you can, I’d try to roll back KEF firmware. The LS50 II’s 4.1.190→4.1.191 update and the LSX II’s 3.0.135 (compiled April 20, 2026) are the clear culprits.

If KEF offers a previous firmware version, downgrade. Check KEF’s community forum, you are almost certainly not alone. Our partners team has reached out to KEF directly around the recent firmware-related issues.

You have our apologies here, Chris! :folded_hands:

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Thanks for the feedback. I reached out to Kef and they suggested they’re going to push a firmware fix, though they quoted version 3.0.135 as the fix for the LSX II’s which you suggest may be the culprit. Will pick up with them again and see if they can push a roll back. Good to hear Roon are liaising with them too, as they’re fantastic speakers and the Roon integration and format variety was critical to me purchasing them.

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Still no resolution with Kef… in case anyone else is having the same problem.

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Following the recent firmware updates v3.0 for the KEF LS60 Wireless and LSX II (both Roon Ready), which - successfully - brought the long awaited Qobuz Connect, unfortunately both speakers won‘t play hi-res DSD and DXD files anymore. As if the v3.0 puts too much strain on their internal processors. In the case of the LS60 W DSD64 still plays, but 2x or 4x DSD won‘t. Neither does DXD 352.8kHz. And with the LSX it‘s even worse: no DSD accepted anymore. I am referring to Roon streams via RAAT and wired Ethernet. I’ve already tried re-boot, switch off, and factory reset, without success, though. Obviously there are workarounds (sample rate conversion within Roon), but it‘s still a hardware feature which is „broken“ by the latest firmware. I opened support tickets with KEF, but am curious to know, whether other fellow Roon users experience the same (or similar). This phenomenon is not the same, but maybe connected to the sample rate/format switch issue discussed by @James_GALT and @alex_h.

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AFAIK, the LS60 never played >DSD64.
Were you having Roon downsample those before but not now?
Besides, the LS60 downsamples everything to 24/96 (wireless) or 24/192 (wired) anyway.

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Although the maximum resolution is not specifically mentioned on the spec sheet (it only states „DSD“), up until firmware 2.6, both the KEF LS60 Wireless as well as the LSX II accepted DSD256. This shows in numerous reviews published following the launch, it is also the standard/default ceiling for DSD when you activate within Roon. And I can tell from experience that my speakers accepted untampered DSD256 streams - until last weeks‘ updates. The fact that, inside the speaker, everything is converted to PCM192 (or 96 for wireless connection to secondary speaker) for KEF’s MIE processing is a different story.

Although I run a Nucleus Titan, converting DSD256 natively to PCM192 is too demanding for the Roon server (at least with the filter settings I prefer, it can only convert at 0.4x speed which is obviously not sufficient) so I chose to stream DSD256 directly to the KEFs. Following the firmware update, this is not possible anymore, and in order to stream DSD256 to the KEFs, I have to either select a less demanding filter settings in MUSE or switch off native DSD conversion within MUSE. These are all workable work-arounds, but they don‘t change the fact that firmware 3.0 is a regression to 2.6 in this respect.

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I’m only rarely using the KEF LSX II for background music, but here I let in every case Roon resampling to max 24/96 (also with interconnect cable, it’s the internal max).

Why are you want to use native dsd processing before resampling? If you’re using some DSPs in the DSD area and after them a converting to PCM, you’ll have only a need for a lot of horse power (which your system doesn’t has) but not a better sound.

Also the speaker itself has in every case DSPs activated and works here in the PCM domain.

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Let‘s please stay on topic. I have started this thread in order to learn whether there are fellow Roon users who can replicate/confirm the issue at hand. I did not mean to start a discussion about whether or not DSD is a useful format (esp. > DSD64) or where DSP conversion should take place (in the server or in the speaker) and how it should be done - and, most importantly, whether or not this makes an audible difference.

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Understood.

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Please don’t misunderstand me (I’m using in a lot of cases DSD also with HQPlayer, but not with the KEF).

I wanted only say, that in your case native DSD resampling doesn’t make a sense…

If you want further send DSD to the KEFs, then you’ve IMHO ask KEF for a solution (they have also changed something in the Roon integration).

12

In my original post I mentioned I opened support tickets with KEF. On this forum, I just want to share my observations following the firmware update and understand whether other members have experienced the same. I am aware that from the Roon angle, the issue cannot be solved.

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I plan on purchasing some LS60s and despite not having an interest in DSD, I am commenting to follow along as I am keen to know how this pans out.

Best of luck with KEF :+1:t2:

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I reported it to them the day it was released, and I immediately noticed the same problem posted above. I told them it had to do with their release and they did not seem to think that it did but they took my information but have never gotten back to me. I’ve gotten around it by using Roon to do the processing for these files…no issues with DSD files on the Kef’s until that April software update.

Doug

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I will post again should I hear back from KEF. My experiences with KEF support in the past were rather irresponsive to negative. For instance, in spring 2024 they introduced Google Cast 2.0 to their speakers (v2.2, May 2024) which effectively reduced all Qobuz App streams (no Qobuz Connect in 2024) to 44.1/16 from previously max. 96/24. I reported this to KEF support, they iterated a few times and asked for numerous screenshots proving the speed of my network connection and the hi-res nature of my Qobuz titles etc., only then to never come back with any response. They were just assuming user error, as usual. Interestingly, the v3.0 firmware (which I complain about in this thread) finally brought workable Google Cast at 96/24 again - almost 2 years after they introduced the problem with their faulty Chromecast implementation. Another example: the introduction of Qobuz Connect has also taken 10 months on the existing LS speaker range. Much longer than with most audio brands. In the meantime, the only response received from KEF support was always “KEF software team is working on it - you can use the KEF Connect App if you want to play Qobuz”. So this is about what you can expect from KEF support in terms of responsiveness and problem solving.

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In response to your first question, yes, I am experiencing the smae problem Playing DSD through the KEF LSXII.

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Likewise here with KEF LS60s

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I’m having the same issue with my KEF LS50 Wireless II. After the recent update DSD will no longer play at all. If I try to resample to the most compatible PCM rate I get random pops and click, sounds like I’m playing vinyl.

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Updated to latest noticing Roon and Roon ARC both failed to play my local .dsf DSD files.

Roon showed “Audio device refused to switch input to Roon” (my audio device is KEF LS60) when trying to play DSD files. But FLAC files are playing ok.

Switched to KEF Connect native app and the same sets of DSD files on NAS are playing normally.

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@Vincent_Lam I moved your post to a thread covering this topic. If this is not correct, I can move it back or you can create a separate Support request thread.