SBC medium, not the larger buffer, removed the headphone relay dropouts, so cut dmix, bluealsa-aplay and alsaloop buffers to 200 ms and the Shairport backend buffer to 0.15 s. Verified by listening (iPhone -> headphones, with AirPlay mixed in) with no RTP loss or underruns. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>