[Elecraft] Sorta OT - assistive technology assistance needed

[Richards]

Good Day.

Background:

I am assisting a blind ham who also suffers some hearing loss.  I 
suggested using headphones to attenuate ambient environmental noise as 
he operates.  The rub is, he needs to hear both his receiver AND his 
computer (which provides audible feedback when logging contacts and 
performing other duties.)

Question:

Can anyone suggest a simple passive (or active) mixer circuit schema I 
can build for him to safely mix audio signals from his transceiver 
headphone jack with audio signals from his computer sound card headphone 
jack?

Discussion:

While there are multiple commercially produced simple and complex mixing 
products in the marketplace, I would prefer to build an inexpensive, 
small footprint solution we can easily incorporate in his station to 
minimize clutter and the number of cables, jacks, and controls -- he 
contends with plenty of that already.   I suppose one solution might be 
a simple Y-adapter cable, but that seems too easy and I wonder whether 
we should isolate the signals and/or grounds in some way?  (e.g., I do 
not wish to cause any "Pin-1" grounding issues, and etc.)

Any traction?   Can anyone point me to an appropriate circuit schematic 
or other resource?  I don 't mind doing homework, and while I enjoy 
building stuff and I am familiar with the basic concepts involved,  I 
could use a leg up on this project, especially to keep it simple and 
easy to build and implement. Please reply off list if this question is 
too far off topic, although I suspect there are many hams who might be 
interested in the result, besides similarly situated disabled operators.

Thank you -  James - K8JHR -
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