Thanks to both. Short version: I fixed it by purging hqplayerd and reinstalling.
Long version
I tried all the things (mainly disabling the devices in roon then reslecting them in the hqplayer web ui) but still no joy. I did notice however in the log an error:
! 2021/10/02 09:54:22 clPlayerDaemon::CreateEngine(): clHQPlayerEngine::Initialize(): clString::ToUInt(): not an integer
(a bit more of the log is pasted below for context)
I tried removing hqplayer with apt-get purge to delete all the configs and reinstalling. I also reinstalled the dependencies as well. Then I reinstalled hqplayer with dpkg and this has worked!
Thanks for the help. A bit more of the log file is included below in case it is useful.
Thanks again - much appreciated
2021/10/02 09:54:21 asoundlib version: 1.2.2
2021/10/02 09:54:21 Found ALSA device: hw:CARD=PCH,DEV=0 - HDA Intel PCH: ALC892 Analog
2021/10/02 09:54:21 Found ALSA device: hw:CARD=PCH,DEV=1 - HDA Intel PCH: ALC892 Digital
2021/10/02 09:54:21 Found ALSA device: hw:CARD=PCH,DEV=3 - HDA Intel PCH: HDMI 0
2021/10/02 09:54:21 Found ALSA device: hw:CARD=PCH,DEV=7 - HDA Intel PCH: HDMI 1
2021/10/02 09:54:21 Found ALSA device: hw:CARD=PCH,DEV=8 - HDA Intel PCH: HDMI 2
2021/10/02 09:54:21 Found ALSA device: hw:CARD=PCH,DEV=9 - HDA Intel PCH: HDMI 3
2021/10/02 09:54:21 Found ALSA device: hw:CARD=PCH,DEV=10 - HDA Intel PCH: HDMI 4
2021/10/02 09:54:21 network Audio IPv6 support disabled
2021/10/02 09:54:21 discovery from 0.0.0.0
& 2021/10/02 09:54:21 discovered network audio: name='UsBridgeSig' version='Signalyst Network Audio Daemon 4.1.1' @192.168.1.58:43210
& 2021/10/02 09:54:21 discovered network audio: name='UsBridgeSig' version='Signalyst Network Audio Daemon 4.1.1' @192.168.1.58:43210
2021/10/02 09:54:22 connect to 192.168.1.58:43210 [ipv4]
2021/10/02 09:54:22 network endpoint: Qutest: USB Audio (hw:CARD=Qutest,DEV=0)
2021/10/02 09:54:22 network endpoint: snd_allo_digione: Allo DigiOne HiFi wm8804-spdif-0 (hw:CARD=sndallodigione,DEV=0)
2021/10/02 09:54:22 CUDA offload requested
2021/10/02 09:54:22 ROCm/HIP offload requested
2021/10/02 09:54:22 libDSP version 21.19.1
2021/10/02 09:54:22 HQPlayer Engine version 4.43.2
2021/10/02 09:54:22 CUDA offload: all
2021/10/02 09:54:22 Number of processor cores: 4
2021/10/02 09:54:22 Core mask: 0000000000000000000000000000000000000000000000000000000000001111
2021/10/02 09:54:22 CPU brand name: GenuineIntel
2021/10/02 09:54:22 Core pinning enabled
2021/10/02 09:54:22 Initial parallel threads: 4
2021/10/02 09:54:22 Number of logical cores: 4
2021/10/02 09:54:22 DSP thread pools disabled
2021/10/02 09:54:22 DSP pipelines disabled
2021/10/02 09:54:22 Pipelined engine enabled
2021/10/02 09:54:22 DirectSDM enabled
2021/10/02 09:54:22 Audio engine: network
! 2021/10/02 09:54:22 clPlayerDaemon::CreateEngine(): clHQPlayerEngine::Initialize(): clString::ToUInt(): not an integer
% 2021/10/02 09:54:22 ...configuration reloaded