I'm very, very impressed, if not blown away with 4H. The adjustment of the TONE and TREBLE knobs makes the pedal sound much more complex than the three knob sounded to my ears.
To me, I hear these pedals becoming more, and more amp like, which I think is a big deal, because they were already amp like! I was trying the 4H through my 68 Twin reverb, with a 62 reissue SG.
I would have played all day with it, as I was super enjoying the sounds, but my naggy downstairs neighbor was pounding on my ceiling communicating displeasure. The superlative tone of the 4h is evidenced by that displeasure.
I used to own a 69 Hiwatt 50 watt, (don't ask why I sold it. Big mistake) and this gets close, close, close. I was enjoying the subtle variations of turning the TONE, and TREBLE 10 oclock'ish and fine tuning them slightly off from each other.
Complex, amp-like. Laney Supergroup Like. Laney Klipp like. Old Marshall Like. Old Hiwatt Like. I was playing riffs from Led ZEP III, and early Black Sabbath, and 4H sounded great.
I am totally into this pedal. Also can be adjusted to sound like Danzig 1. I hope this is giving some idea of the sounds of the 4H. My initial impression is that I very much prefer it to the 3 knob.
More later, and I apologize for not being a great communicator, just trying my best to express! Looking forward to hearing from the smart 4H owners!-Tim