Duplication only does what standard routing does

[Simran-B]

I tried to achieve the following:

Audio source ━━━┳━━━▶ Virtual Audio Cable
                ┃
                ┗━━━▶ Laptop speakers

The audio source is routed to either the speakers or the virtual audio cable, without the help of audio-router.

Now, I would like to duplicate the audio signal and output it to both, but if I use the Duplicate option in audio-router (soft or not), from there on the signal is only sent to the audio device I choose. I verified that by using Audacity to capture the signal, but there is nothing to capture on the virtual audio cable line (anymore) if I duplicate to the speakers.

I'm using Windows 10 Pro 64bit, Build 14393, running on a MacBook Air with Bootcamp 6.0. Virtual Audio Cable v4.14. Speakers: Cirrus Logic CS4208 (AB 114) with default driver by Microsoft (v10.0.14393.0, 2016-07-15).

[audiorouterdev]

For the duplication to work correctly, you need to first route(or duplicate, the very first routing is equivalent in both ways) the audio to a single device, and after that duplicate it from there to another device. Unfortunately the duplication is somewhat counterintuitive at the moment.

[Simran-B]

I see. Here are my findings:

• Groove music app (windows.media.backgroundplayback.exe) can't be routed at all: Error code 0x00000005: Access denied. Router functionality not available.
• Windows media player doesn't fully work: I can route to the speakers, but if I duplicate from there to Apowersoft_AudioDevice or Virtual Audio Cable, there is no signal on the latter, but it keeps playing on the speakers. If I route to Apowersoft_AudioDevice, and duplicate from there to the speakers, there is a signal on the former, but I can't hear it playing through the speakers. The speakers show up as separate group, but only with one fader (the speakers themselves, with a mute button), but the group misses the media player as input (second fader with menu button). Soft routing doesn't work at all, or if used for the duplication, it will be stuck at "duplication pending".
• Using VLC, iTunes, QuickTimePlayer or Spotify as music source and Apowersoft_AudioDevice, I can route/duplicate either way without problems.
• Virtual Audio Cable seems to be broken, if I route to it, there's no signal showing in audio-router anymore and if I duplicate to the speakers, there is no audio either. Routing it back to the speakers gets the audio back. If I duplicate from the speakers to Virtual Audio Cable, I keep hearing the audio signal but there's no signal on Virtual Audio Cable. With Apowersoft_AudioDevice, I can route from and to it without issues.
• In general, if I route to a virtual audio device and also have it play on the speakers, or use Windows' native feature to play an input device on the speakers (successfully tested with Spotify routed to Virtual Audio Cable with a 3rd party plugin), it seems to record the audio fine (e.g. Audacity), but on the speakers, there are some scratching noises (temporary buffer over- or underruns?) every now and then. Not sure if this is an issue specific to the audio chipset used, or maybe caused by a not powerful enough CPU (only a single core can be used I guess and it usually runs at 2 GHz, which might get under full load sporadically if there's a concurrent background task run on it).

[Simran-B]

Also tried my desktop computer with Windows 10 and a Realtek audio chip / driver in combination with http://vb-audio.pagesperso-orange.fr/Cable/index.htm and audio-router. I successfully routed Spotify to the speakers and duplicated it from there to VB-Cable. The only problem I ran into is that after quitting audio-router, the audio is gone entirely and I had to restart Spotify.