How can I aggregate two identical Tascam audio interfaces?

Hi,

I am running Logic ProX on late 2016 MacBook Pro and have two Tascam US-16x08 USB audio interfaces. I need the multiple inputs as this allows me to multi-track record bands live using up to 16 microphones. I have previously created an aggregated audio device using a single US-16x08 and a completely different audio interface with no problem, the resultant aggregated device appearing in Logic with all inputs of both devices available. However, when attempting to create an aggregated device with two US-16x08s, only one device is ever visible within the OSX Audio Setup window so I am unable to create an aggregated device consisting of two US-16x08s.

I have spoken to Apple support who say this is an issue with the device so I have also spoken to Tascam who will only say that it is not possible to aggregate two USx16-08s. I assume this problem is likely to be the same for other Tascam audio devices and have seen posts regarding similar issues with multiple, identical USB microphones. I have seen some suggestions that the Soundflower app might be a solution but this appears to only allow routing between devices and applications that the Mac can 'see.' As the Mac can only 'see' one device, I don't think Soundflower will help. I have also read that this may be caused by Apple's implementation of the USB standard, i.e. that although each device will have a unique number, macOS is ignoring that and seeing the two devices as being the same thing (but only allowing connection to one).

Possible solutions might be;

1. Using a 3rd party app to provide a workaround, if one exists,

2. Changing the way macOS handles USB identities,

3. Changing the USB identity of one of the devices, perhaps through firmware, or

4. Selling one of the Tascam devices and buying a second interface from another manufacturer!

I seem to now be stuck between Apple and Tascam, neither of whom can offer a solution. This is particularly frustrating as Apple supposedly hold the multimedia 'crown' and Tascam claim to supply professional audio equipment but there is clearly a problem between the two of them.

So I thought I would turn to the Apple community for help. I have trawled many forums for a solution without success but apologies if I've missed something really obvious. I'm sure I'm not alone with this issue. Any suggestions would be gratefully received. Thanks.

Psy.