I have an Eleven rack which I'm trying to decide whether to keep or sell. Now running through the Firebox as an IR loader using either the FX send or out to amplifier jack. This improves the Eleven rack somewhat. However if all 11R blocks are bypassed so that I can use the Firebox in the signal chain there's a high pitched whine that doesn't stop when 11R levels are dropped. I'm leaning towards just using the 11r as bass amp with an Atomic Reactor cab for the odd bass student. What's the best way to route signal for IR loading? Thank you.