My HPF is right BEFORE my SLO and I have no "boom". The SLO won't produce what isn't there. My microThumpinator cuts everything below 30hz so the signal that his my SLO doesn't have all the mud in it. I have a loop pedal on my board which allows me to bypass my entire pedal chain and go straight to the SLO in the event there is some issue, cable short...whatever. And I can tell you that the Thumpinator makes a tremendous difference. It allows the preamp to deal only with sonic content...not all the subsonic junk that is prone to cause distortion.
The Thumpinator is the last stop before the SLO on the road to tone bliss.
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