Roon Bridge on RasPi (Volumio) only 16 bit

Core Machine (Operating system/System info/Roon build number)

Network Details (Including networking gear model/manufacturer and if on WiFi/Ethernet)

Audio Devices (Specify what device you’re using and its connection type - USB/HDMI/etc.)
RasPi4, Volumio, RoonBridge 1.0 in NanoAvr

Description Of Issue
Roon‘s output to my RasPi4 RoonBridge gets down converted to 16bit. If I feed my NanoAvr with HDMI from my Oppo103 receiving audio from my Win10 HDMI PC no conversion happens from Roon and my NanoAvr received a 24 bit signal.

If I feed that NanoAvr from an Raspi4Hdmi via Volumio & Roonbridge from my Win10 Ethernet path, Roon converts everything to 16 bit.

Whose limitation is that?

Somehow Roon must sense that 16 bit conversion is needed for the RasPi path - how?

(Likewise, if I let Roon‘s DSP upsample everything to 192khz, Roon somewhere does a last minute change and only pushes 92khz to the Raspi4, but that is Ok since the NanoAVR only takes 96 kHz anyway)

Seems the same issue as here.

Thanks. Yes, same issue. On the other hand, I directly compared the Oppo 24bit vs the Raspi 16bit stream going into my NanoAvr - the Raspi sounded a bit better… . I guess RAAT - Raspi beats PC-Hdmi.

24bit with Hifiberry Dacplus

Hi @Joachim_Strobel,

This is a Rasberry Pi ALSA limitation, please see:

That is hardly true.
Via HDMI I get 16bit/96khz out. Via the Hifiberry DAC+ I get 24 bit. Is it then not using Alsa? Elsewhere it was said by one poster that the HDMI chip is limited to 48khz, while others, incl Mr Volumio, proofed that to be wrong.

The alsa driver for the HDMI port is limited to 16 bit. Other hardware has different alsa drivers. So via HATs like the hifiberry dacs it’s possible to output 24 bit.


As said before: Roon puts 30 bit into my Oppo103 via HDMI (from PC-Asio4All), that gets dithered down to 24 bit for my NanoAVR. The other route is RAAT into Volumio/Raspi4 in 16 bit from Roon and then via HDMI into the same NanoAVR (and then Dirac, DA into preamp and amp). The Volumio stream sounds slightly better and is more elegant…

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