Reviving this thread!
I was doing floor tunings in a local piano store when a customer came in and started playing different instruments around me which essentially stopped me in my tracks from completing my tuning...and then I remembered reading this thread and thought this might be the solution.
Frank, do you feel the hardware you mentioned worked well enough to use this with accuracy? If I understand this setup correctly, absent the ability to have simultaneous monitoring via earbuds, you need to rely on the visual display? I find I use pianoscope to tune one string and then aurally tune the others to it—it would be really valuable to be able to continue this method in a noisy environment using the contact mic and earbuds.