niveau de la sortie casque bas ?

The Babyface’s headphone amp has attracted criticism in some quarters for being unable to put out a loud enough signal, a consequence of its being powered from the 5V USB connector. Whether or not this is a problem for you is likely to depend on what headphones you use. At our drum session, the drummer was playing — very loudly — along to some previously recorded backing tracks which consisted mostly of acoustic guitar. He was receiving the signal from the dual‑purpose line out/duplicate headphone out on the Babyface’s breakout cable, while I monitored simultaneously on the main headphone out. This, in theory, should have been an absolute worst‑case scenario, since the duplicate output is lower in level than the main out, and plugging two pairs of phones in drops the level, as both are driven from the same amp. As it turned out, turning the headphone control all the way up gave him an adequate level on his KRK KNS8400 phones, while the level on my Sony MDR7509s was also perfectly healthy. However, both of these phones are very low‑impedance designs, which are consequently very easy to drive, and given that there was no additional room for manoeuvre, I can see that other models might be problematic.