As discussed elsewhere, the problem of incompatibility is most likely caused by the aircraft. If the aircraft has a quality intercom then each of the headsets has its own amplifier and they all work OK.
To save money, some installations don't have an intercom or have a cheap one where all the headsets share an input amplifier. All the headsets are wired in together and if their impedances are different (ie different manufacturers) there will be times when they don't match correctly. Thus using two different headsets will cause a problem. Very difficult to predict which ones will work together. In almost all cases two of the same make will work together.
Having a popular brand such as DC will help as they are very common and many instructors use them. XYZ cheapos are probably more likely to be incompatible.
ZA