Schorly, just for clarification, the Aestheitx Io inserts the volume control and single high level input in front of the last gain stage. The Io was designed by Jim White to directly drive an amp to full output. So, it has an active "line stage," but not on par with the dedicated full-function line stage of the Callisto. I don't know how the Steelhead is constructed in this regard, but I would suspect it's similar.
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