You mention radio signals when you record. When this occurs, Is the Lynn turntable the source? I ask because improper ground at the turntable and /or phono stage often results in the reception of all kinds of RF signals, even ham radio and CB.
Try improving the grounds at the phono end of the system first. Then, you may be able to float the ground to your amps with no radio AND no hummmmmmmm.
Try improving the grounds at the phono end of the system first. Then, you may be able to float the ground to your amps with no radio AND no hummmmmmmm.