Greetings... I am having the same problem when the volume is up any... I've a Studio Channel, an Avalon 737 and (another Preamp/ Compressor/ EQ I am not trying till I figure out what's up )... I have used the Pipeline Plug-in ( Look-Listen-Learn guys on YouTube explain well ), but the signal seems too hot with any of hardware, resulting in that loud screech/ hum. Lastly, when I close/ quit the song, the sounds comes into play at a low level.
Hope you find the answer brother. I'll try again tomorrow and pose my question, or offer and answer... depending what I find with a fresh/ less frazzled mind.