There was an interesting recent thread on BCP about using older non-TSO'd avionics on a Cessna 170 that was produced under older CAR-3 regulations.
https://www.backcountrypilot.org/community/forum/latest/non-tso-d-instruments-14484
It got me to wondering what the deal was on TSO vs. non-TSO approved aviation headsets.
Does plug in vs. permanently attached make a difference ? What about ANR vs regular non-TSO headsets? What about TSO approved headsets for IFR or ADSB?
Anyway, I came across this article which had a lot of the answers.
http://uflymike.com/media/documents/UntanglingtheAirlinePilot-TSOHeadsetControversy.pdf
