For a stem-mastering, you render certain sounds of your production (for example bassdrum, bassline, percussions, sequences) in separate Wave files.
When running all these stems together, the production should sound the same as your original.
Like this, I have much more possibilities to optimize the individual sounds and eliminate typical problems like a "weak" bassdrum compared to the bassline.
I will not add any "creative" sounddesign like effects etc. as this is part of my mixdown service.
Delivery procedure is the same as mastering.
Click here for a detailed list of how you should prepare the stems