I used parallel compression in the mixer, the step was to send an auxiliary aux to rtn (I don’t know if this is the right operation), and insert compress plugin in rtn, but the final effect sound not quite the same in daw effect, it like the sound of rtn was slower than the sound of grp, resulting in a flanger effect.
Each send introduces a fixed amount of latency to the signal routed through that send, in order to prevent feedback loops. This means that if you want to use two different parallel copies of a signal and keep them perfectly synchronized, you must ensure that both routing paths contain the same number of sends.
I suggest creating a new return bus and adding a pre-fader send targeting that return bus to your group bus, and setting the group bus’ fader volume to -oo dB.
Thank you, I got it,Great solution!