Audio One audio source is louder than the rest

I have an audio source in my title screen, and when it switches to the main menu, which is in a different scene, the volume is quieter. I've checked both audio sources in the inspector, and they both have the same volume level, since they're both getting the value from PlayerPrefs. The volume throughout the game is the same as in the main menu, but the title screen is always louder.

I've spent a lot of time trying to figure out why the audio in one scene would be louder. If anyone has had this happen, I would love some help. This is driving me crazy!

 

Edit: I've made sure there's only one audio source in the title screen, so I know that's not the problem. I also disabled the audio source in the title screen, and when the audio source in the main menu played, it was at the proper volume.

But when the audio source first plays in the title screen, the audio volume is quieter in the main menu. I'm at a loss at what the problem could be. It's not really noticeable when the volume is within the top 25%, but quite noticeable anywhere below that.