Fugue - Free and premium stock music for your videos, games, and UI
EarTrumpet - Volume Control for Windows
Soundstripe - Unlimited music for video
Sound Control - App-specific volume control
TunePocket - Download 11,000+ royalty free music tracks and sound FX. Buy once, use forever. New music added daily. Save over 50% compared to most popular similar services. Incredible value!
Power mixer - Power Mixer is a complete Windows volume control replacement.