The Amplivox Amplilite headset on this page belonged to A.R., a well-known test pilot, who was active in the KTA before 1944 and in the DMP afterwards, flying nearly all the aircraft and helicopters of the time, totalling more than 5400 flight hours until his retirement in 1981.
Most probably a private purchase that presents an interesting detail: the comm cable has been lengthened to a length of one metre and eighty centimetres. The probable reason can be seen in the photo below...
Note: the above degraded image is taken from the book "Werkflug-vol d'usine” by Bernard Jaggi, for educational purposes only in accordance with the Berne Convention, Art. 10.