I swear it's different from the billion other Echidnas I posted, it's actually my first time running Sonatina in a really long time. I also played with fairly high Specialization. Uptime split on Serenade was 20% on 2 Bar and 50% on 3 Bar.
With these stats, the 3 Bar buffs give about 2.2% more final damage than from a full swift Bard, which is quite a lot of damage.
Apologies for my cursor going crazy. I started using Steam recording and it's very convenient for me, but I'm not sure yet about how to solve it. I just hope it's not too distracting !
Echidna - 00:00
Build - 09:16