Parallel mastering is a technique used in audio mastering in a DAW to create a blend between the original unprocessed audio and a parallel processed version of the same audio. This is achieved by duplicating the original audio and processing one of the copies with additional effects, such as compression, EQ, or saturation, and then blending the two signals together.

The benefit of parallel mastering is that it allows for the processing of individual elements of the mix without compromising the overall balance and dynamics. By using parallel processing, you can add energy and impact to the mix without sacrificing the clarity and depth.

The best mastering chain including level detail can vary depending on the material being mastered and the personal preferences of the mastering engineer. However, a common starting point for a mastering chain might include the following:

1. Gain staging: Adjust the levels of the mix to ensure that the loudest part of the mix is hitting the mastering plugins at around -6 dB.
2. EQ: Use an EQ to shape the tonal balance of the mix, removing any unwanted resonances and boosting or cutting frequencies to achieve the desired sound.
3. Compression: Use a compressor to control the dynamic range of the mix, bringing up the quieter elements and reducing the peaks.
4. Saturation: Add subtle saturation to the mix to add warmth and character.
5. Stereo widening: Use a stereo widener to enhance the stereo image of the mix and add depth and dimension.
6. Limiting: Use a limiter to ensure that the overall level of the mix is consistent and competitive with other commercial releases.

It’s important to note that the mastering chain should always be adapted to the specific needs of the mix being mastered, and the processing should always be used in moderation to avoid over-processing and loss of quality.