Voice input volume (adding notes—not playback) much softer than other instruments

Does anyone know how to change the volume of certain voices during input? I transcribe a lot of choral music, and this has been very frustrating for me. Instrument notes sound loud and clear, but every time I'm writing the voice parts, the volume is so low I can barely hear the notes as I add them. If I turn the volume up on my computer, I get blasted when I add piano/organ/etc. Playback is fine (via dynamics), no issues there.

I've searched the handbook/forums, but haven't found a way to fix this issue. Any ideas?