jtdoherty wrote:

I’m getting a small volume drop just enough to take the edge off the amp when the HD is in the Signal chain.

A few questions to determine what could be causing the change in volume:
-Are both H90 paths being routed to the front of the amp?
-Is either path being directed to the amp’s effects loop?
-What other effects are in the signal chain along with the H90?

jtdoherty wrote:

I have lip and lick with the drives in between.

I’m not sure what you are saying here. Are you saying you have drives in between both H90 paths?