The Creme combines a passive EQ based on the Pultec principle and a high end bus compressor in a single device.
Many successful mixing engineers share one thing in common: They mix with a compressor and EQ in the master channel. The EQ is usually set to subtly boost the bass and treble, while the bus compressor compresses the sound by a couple of dB.
This gives the engineer an idea of how the mix will sound after mastering, even still during in the mixing stage. It also helps in finding the right volume balance for individual sounds (especially vocals).
The bus compressor has a few additional functions such as a low-pass filter for the side chain and an additional ratio of 1.5:1 for especially subtle compression.
The placement of the EQ and compressor in the mix can also be switched.
Similarly, the Creme is suitable for use in mastering as well.