Erm. Actually its on the right click menu on the renderer...
Sorry for reviving this old topic but I'm having the same problem as the OP. Can't get gapless to work with my new Cambridge 851N using JRiver/JRemote. I've run your analyzer program and have the following result:
DMR Report (by Whitebear) for 851N
==================================
Device Description Url=http://192.168.1.78:8050/8688f491-5d69-4a21-97d3-1daf40f3bd9a/description.xml
HTTP Server Header=StreamMagic UPnP/1.0 Radio/1.0 DLNADOC/1.50
Friendly Name=851N
Manufacturer Name=Cambridge Audio
Manufacturer Url=http://www.cambridgeaudio.com/
Model Name=851N
Model Number=2504
Serial Number=000caf83
UPnP Device Type=urn:schemas-upnp-org:device:MediaRenderer:1
UPnP Media Renderer version=1
Unique Device Name=uuid:8688f491-5d69-4a21-97d3-1daf40f3bd9a
X_DLNADOC Element=DMR-1.50
Service Url for RenderingControl=http://192.168.1.78:8050/8688f491-5d69-4a21-97d3-1daf40f3bd9a/RenderingControl/RenderingControl1.xml
Service Url for ConnectionManager=http://192.168.1.78:8050/8688f491-5d69-4a21-97d3-1daf40f3bd9a/ConnectionManager/ConnectionManager1.xml
Service Url for ContentDirectory=http://192.168.1.78:8050/8688f491-5d69-4a21-97d3-1daf40f3bd9a/ContentDirectory/ContentDirectory1.xml
Service Url for AVTransport=http://192.168.1.78:8050/8688f491-5d69-4a21-97d3-1daf40f3bd9a/AVTransport/AVTransport1.xml
AVT:SetNextAVTransportURI (gapless play)=Supported
AVT:SyncPlay (synchronous play)=Feature not available on this DMR version
RC:GetVolume action=Supported
RC:SetVolume action=Supported
AVT:Event Subscription=Fail
Play test file result=Play success => Start Ok / Stop Ok / Subscribe error
Media Center DLNA Server Advanced Settings
==========================================
DLNA=Checked
DLNAExtra=Checked
Enable bitrate Field=Checked
Filter international characters=Off
Include session ID=Off
Playstation 3 Compatible=Off
Present Caption Resources=Checked
Present Small Artwork=Off
Present Subtitle Resources=Checked
Skip Child Count=Off
Use flat URLs=Off
Use full URLs=Off
WMC Compatible=Off
Declared Supported Audio, Image & Video Formats
===============================================
http-get:*:audio/L16:DLNA.ORG_PN=LPCM
http-get:*:audio/mpeg:DLNA.ORG_PN=MP3
http-get:*:audio/mpegurl:*
http-get:*:audio/x-ms-wma:*
http-get:*:audio/L16:*
http-get:*:audio/mpeg:*
http-get:*:audio/*:*
Evaluated Supported Audio Formats
=================================
audio/L16 LPCM Dlna 48000 2 16 Yes
audio/mpeg MP3 Dlna * 2 * No
audio/x-ms-wma WMABASE Fuzzy * 2 * No
audio/L16 LPCM Fuzzy 48000 2 16 Yes
audio/mpeg MP3 Fuzzy * 2 * No
audio/mpegurl Undefined
audio/* Undefined
As far as I can tell this report claims that SetNextAVTransportURI is supported. If so, any idea why I don't get gapless playback? I've contacted Cambridge on this issue and they claim they can't get gapless to work with JRiver either. Perhaps there is a setting we are overlooking?
Thanks for your help.