proposal of DAP using an inexpensive TAS5162 amplifier chipset and Raspberry Pi
Raspberry Pi
↓ I2S protocol
TAS5508C
↓ PWM signal
TAS5162 *2 (PBTL)
↓ sound
Passive Speakers
▶ 6Ω, 4W = 0.005% THD+N
If you limit the output, you can use an inexpensive DC Power supply.
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▷ 4Ω, 200w...