DiscApe

I have a D777, most people talk about the famous SQ of this player, but with ESP turned on, does it use the ADPCM compression feature? SOme say its uncompressed others say it not. To me it seems like with ESP turned off it's better, but can't be sure I'm not being fooled. As the CD keeps skipping without ESP on, it would be great if anyone can help with this technical question.