I will say this one more time ,this thing about matched headsets is rubbish ,if the intercom system is up to scratch then it will take headsets of different types (providing that the headset is servicable).
If you have problems with different headsets then you have an intercom problem.
This could be /1 no intercom fitted and the audio using the radio as an amp. /2 an old intercom probably more than 15 years old ./3 the intercom has lost the amp in one audio channel.
For some reason that I am unable to descover people will except radio and audio problems in aircraft that they would never except with a mobile phone or a hi-fi system and use myths like "matched headsets" to mask the fact that what they have is a sub-standard intercom.
The solution to the problem is to fit an modern intercom the best are in my opinion made by PS engineering , garmin and king with the latest sigtronics units a close second.