https://www.strongtie.com/joistframingconnectors_coldformedsteelconstruction/huc_hanger/p/huc
https://www.homedepot.com/p/Simpson-Strong-Tie-HH-Galvanized-Header-Hanger-for-4x-Nominal-Lumber-HH4/100375280
Either one would be fine. Can't tell you if the (2) 2x4 holds the weight of the piano...
Hang the new header with either HUC24-2 hangers or HH4 hanger at each end to the existing king studs. This eliminates the need for adding trimmers (jack studs).