A big maybe. While 20MHz TMS32010 DSP in 1985 was around 386DX 33MHz horsepower wise, if you ignore things like single cycle 16x16 multiply(10-20 faster than 386), it might still be too slow. For comparison ~3x faster DSP56001 in Atari Falcon needs 16MHz CPU assist to decode MP3.
Comparing to a general purpose CPU, I remember from the olden days that a 486 DX4/100 was just BARELY able to decode stereo MP3's if you used a well optimized MS-DOS playback program. In a multitasking environment like Windows -- forget about it!
