Remaster My 25-Year-Old Track

I have a single music piece that was recorded 25 years ago and now survives only as a digital file (I can supply either MP3 or WAV). Age has left it sounding flat and dated, and I want a fresh master that feels clear and full without losing the original character... (Budget: $750 - $1500 USD, Jobs: Audio Editing, Audio Engineering, Audio Mastering, Audio Production, Audio Services, Music, Music Production, Sound Design)