You can use Reaper to slow down tracks, so you can pick out fast passages more easily. Plus, you can EQ to hear even better. Here’s a video . . .
It’s simple . . .
- Import an MP3 of the track
- Cut out everything but the part you want to learn
- Hold down the ALT key (‘Option’ on a Mac), and hover over the end of the of the track. Click and drag to the right to slow down the track without changing the pitch
- EQ the track: high pass, low pass and boost mids
While this isn’t magic, it will make learning those fast passages much easier.