The owner may have interpretted as bad multiway mains connector.

This capacitor was .2 inch spacing, same as the one over the bridge for the
tweeter amp supplies. That shows no heating at all. That one is mustard
yellow 6x2.4x4.2mm high, marked
K2R
104K
That one must be 100 V rating at least, so probably MLCC for that size,
certainly if 200 V rating. The burnt one , same footprint may have been
taller or 100V rating only. Probably started with metal migration and MLCC
failure , yet again , starting with going ohmic down internal
micro-fractures then conflagration eventually, rather than bad adapter
leading to multiple mains spikes