SV_IREG_MPU401
snd_sonicvibes_out(sonic, SV_IREG_MPU401, sonic->mpu_switch = 0x05); /* MPU-401 switch */
SONICVIBES_SINGLE("SonicVibes Onboard Synth", 0, SV_IREG_MPU401, 0, 1, 0),
SONICVIBES_SINGLE("SonicVibes External Rx to Synth", 0, SV_IREG_MPU401, 1, 1, 0),
SONICVIBES_SINGLE("SonicVibes External Tx", 0, SV_IREG_MPU401, 2, 1, 0)