^^ nice comment. There is something you miss, however...
The S series doesn't have an S-master amp, however. It is a shame, but the current crop of S-master is limited to the top A 840 series and X models only.
You seem to agree with one of my comments and disagree with others can you clarify with which comment you agree?
Sony's and Senn's frequency responses are within 6 db and also verified by other labs. IEMs go faster but when in the canal suffer sharp role-off something that I never understood in the past and did not pay any attention to it as I had not noticed any difference.
However I recently became aware of it and I could not believe it when I was experimenting with my A818 and S739 IEMs and my SA-5000 and Westone 3. The 818 was better when wearing IEMs and worst when wearing the SA-5000. I was eperimenting with A818 and S739 because their difference was kind of like the difference between the X and new A series and I wanted to make up my mind as to which of the two I should upgrade to.
The S series is said to have an S master amp in Sony docs. However I am also not sure whether this is true and not a mistake given that the S may have been misinterpreted. Do you know something more on this?