OBS outputs mono sound only from capture card. Help!

[Deelite]

Hello all. I've recently just bought a HDMI to USB capture card dongle from Amazon and have it capturing a Firestick output to my MacBook. Picture is absolutely fine. Problem is, I can only capture mono sound from the stream. I've tried every kind of audio setting on OBS, the MacBook and on the Firestick but to no avail. System Preferences sees it as USB3. 0 capture. The selected device has no input controls.
So, after a lot of web searching I've come across what may be the problem. It's the capture card's audio output. Apparently a lot of the cheaper Chinese made dongles output audio as 1 channel 96khz 16 bit (2 x 48khz channels combined) which my Mac only sees as 1 channel of audio. Audio Midi utility shows it as USB 3.0 capture 1 in / 0 out with Format - 96,000 hz 1 ch 16 bit integer. There is no way to alter this via this utility.
My question is, is there a workaround for this? Can I use a specific piece of software or a Terminal command to split the audio stream coming in via USB to the correct stereo channels? Any advice would be greatly appreciated!

System Information shows the card as follows:

USB3. 0 capture:
Product ID: 0x2109
Vendor ID: 0x534d
Version: 21.00
Speed: Up to 480 Mb/s
Manufacturer: MACROSILICON
Location ID: 0x14200000 / 6
Current Available (mA): 500
Current Required (mA): 500
Extra Operating Current (mA): 0

MacBook Pro 9.1 running Catalina 10.15.7 (maximum available on this model))
OBS version 19.0.2 - 64 bit (maximum available on this model)

 

[Deelite]

Okay. So, I've installed the iShowU audio capture thing and tried all sorts of configurations and, NOTHING. At best no sound. At worst, massive, massive feedback from built in Mic (which wasn't even selected as a source)!
Stumped!

 

[Deelite]

Okay. So I’ve sent the cheapie hdmi capture card back and found a really neat solution to the problem. Well, it’s not neat as in tidy but it works well.
Bought the UGREEN hdmi video capture card CM630. It costs a little more than the Chidongles though not as much as an Elgato and so far it’s worth it. This is a nicely made little box with plenty of options for connecting peripheral devices like mics and headphones etc. Instantly recognised by the Mac. Looking at the specs, it utilises a couple of decent ICs for video and audio compared to the single one in the cheaper dongles.
The unit outputs stereo audio channels correctly and has the added advantage of a 3.5mm audio out jack connector if things get too complicated. I can also connect it to a TV and monitor the video as I capture. The unit runs cool so no overheating worries here.
Video is noticeably better than the previous device too. Colours are nice and natural. Yes, it has HDCP built in though I already had the solution to this via a eSynic HDMI splitter I had laying around. Working like a charm with OBS.
So far so good!