I prefer film cap for audio than OS-CON.
For these reasons:
1. It has far less harmonic noise.
2. It has far less parasitic inductance and resistance which adds to thermal noise.
(The name of the game is to lower the resistance right? Then why use OS-CON or al. cap for that matter?)
3. It has far less distortion. (important. Unless you want the uncontrolled distortion. Don't get me wrong.
I like the warm distortion sound, but dude, gotta get real.)
4. It is virtually un-breakable.
5. MTBF is practically infinite. (well, OK, you won't listen to your portable device after 10 years.)
6. No polarity is needed. (Sound is good when you have negative and positive polarity.)
7. No piezo like ceramic class II. OK, class I is OK, but who makes 100uF class I ceramic cap for
Class D amp? (you don't want your pcb buzzing at less than 20KHz.)
8. No DC bias. (this cause distortion.)
9. No temperature bias. (this adds to distortion and noise.)
Well, OK, here is the cons for using film cap. This is why nobody use this for the portable audio.
1. The film cap is very very expensive compared to OS-CON for the same size capacitance.
2. The film cap is big. Well, who wants that on the portable device like iPhone?
From that stand point, I tolerate even tantalum cap over OS-CON. Sony must be hallucinating to
promote OS-CON. A real man goes for film cap.