Audio updates from more bench testing

[erichelgeson]

Follow up to #449 as I tested more scenarios and edge cases. Also working on a PIO/SM/DMA audit/build time check to avoid issues earlier

[github-actions]

Test this PR

Flash the firmware built from 7eb1685: BlueSCSI binaries.zip

• see Updating Firmware for how to flash it.

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BlueSCSI Memory Report

Compared against release v2026.08.17

Memory Usage

Target	FLASH	RAM	SCRATCH_X	SCRATCH_Y
Pico_2_Audio_SPDIF	688.5 KB (+2.9 KB) [34%]	511.7 KB [100%]	3.5 KB [88%]	3.8 KB [94%]
Pico_2_DaynaPORT	680.6 KB (+2.6 KB) [33%]	511.7 KB [100%]	3.5 KB [88%]	3.0 KB [75%]
Pico_Audio_SPDIF	711.5 KB (+3.1 KB) [35%]	252.4 KB [99%]	1.5 KB [38%]	768 B [19%]
Pico_DaynaPORT	703.1 KB (+2.8 KB) [34%]	246.3 KB [96%]	1.5 KB [38%]	—
Ultra	698.0 KB (+2.6 KB) [34%]	511.7 KB [100%]	3.5 KB [88%]	3.0 KB [75%]
Ultra_Wide	456.5 KB (+2.4 KB) [22%]	511.7 KB [100%]	2.0 KB [50%]	3.0 KB [75%]

Symbol Region Changes

Pico_Audio_SPDIF: 5 symbols moved RAM → FLASH (-472 B RAM)

Symbol	Size
pio_sm_set_pins	160 B
void logmsg<char const*, char const*>(char const*, char const*)	80 B
void logmsg<char const*, char*>(char const*, char*)	80 B
void logmsg<char const*, unsigned long>(char const*, unsigned long)	80 B
void logmsg<char const*>(char const*)	72 B

Pico_DaynaPORT: 5 symbols moved RAM → FLASH (-472 B RAM)

Symbol	Size
pio_sm_set_pins	160 B
void logmsg<char const*, char const*>(char const*, char const*)	80 B
void logmsg<char const*, char*>(char const*, char*)	80 B
void logmsg<char const*, unsigned long>(char const*, unsigned long)	80 B
void logmsg<char const*>(char const*)	72 B