Adjust at the preamp if you have that functionality. Otherwise leave alone.
Subwoofer adjustment for each recording
I have dual REL subwoofers using high level speaker out connections as recommended by REL. I have KEF LS50 meta speakers. I am happy with my subwoofer crossover and volume settings most of the time. However, with some recordings the bass seems too strong. Should I adjust the bass at the subwoofer? Should I adjust the bass with my preamp? Should I just listen to the music as is, since this is what the producer, engineer, or musician wanted. Thanks.