My first Broughton arrived today; I'm in the club now. My initial observation about the always-on HPF is that it makes my Ampeg PF20T sound like a much more powerful amp. My second observation is I love the way the HPF changes the character of pedals that come after. I just tried it before my Fairfield Barbershop, and noticed that a sweep of the HPF frequency brings out a lot of useful variations in the overdrive. I look forward to future Broughton Audio GAS.