The SNES sound chip was created by Sony and is 90% the same as the sound chip in the Playstation and PS2. It had 64k and played back ADPCM compressed sound using 8 channels. The compression effectively gave you three times more RAM, but meant that if you used looping sounds, you had to set the loop points on multiples of 16. The Playstation has 512k with 24 channels (and loop points on bizarre multiples of 28). PS2 has 2Mb and is basically just two PS1 sound chips. <sarcasm>Hurray for Sony's audio hardware department</sarcasm>.
The Mega-CD was insane. The audio hardware could playback sound at MHz speed, and yet there was only 64k RAM. It didn't have hardware compression. We had a Protracker player and I just did all the music in four channels in Protracker.