One of my favourite Sybian scenes is by Avy Scott and Kylie. If I remember Avy had the Sybian whilst Kylie had to make do (!) with an Hitachi Wand sitting on the end of the Sybian and yes it was quieter. Mind I have also got a mindblowing solo set Kylie did for yet another site with her usual "moist" climax fair buzzing off the Sybian.
Actually the second set was on a mattress or similar as well. Maybe good soundproofing as long as the bed is big enough.