I dont’ want user to understand it as “listen binging your episodes or taking it slow”.
Using “modifiez” is less ambiguous than “adaptez” about that. There is no doubt you are speaking about changing playback speed. If not for that “adaptez” is better.
Either way I would drop “selon vos envies” because when you change a settings it’s because you prefer it that way. To write it is a little redundant and I think it’s better to have a shorter text.
To sum it up : “adaptez” is better, let’s use that.
And to correctly convey that we are speaking about the ability to change playback speed it would really help to have screenshot showing speed selection. All the more since we should have a nice dialog UI in 2.0.0. What do you think? (Everybody not just Keunes 
)
I’d like to speak a little bit more about screenshot with “adapt Antenna to your need”. It is somewhat similar to “selon vos envies”. Basically we are saying “hey this apps has settings and guess what ? You can change them!”
That’s why I am for dropping this one and make a screen promoting that Antenna is totally free and there isn’t anything to paid to benefit from all it’s features. It sounds a lot more attractive. 
(All others screen promote something)