My earlier reply to an inquiry on using the MP and PSK-31 didn't clear the system, so here it is again ... You do not need an interface box such as Rigblaster. I use a Soundblaster card with these hookups: Soundcard line out to MP Phone Patch In. MP AF out to soundcard line in. Adjust transmit level using sound card gain for proper ALC. Engage the vox. Unplug your mic. Go to town on PSK-31 (!) -Bill