After 22 minutes of playing pink noise at 50% volume into a pair of KEF LS50¹:
temperature_cpu: 42
temperature_tmp102: 42
Case temperature, manually measured: 29.2⁰C
Footnote 1:
50% volume into KEF LS50 is not as well defined a boundary condition as one might think. Actual power output depends on my RC settings and volume limit, it's just a rule of thumb value.