I'm doing a review on the Maxon CP-9 pro+ compressor as a small contribution at the time being as I have found this some completely amazing and have yet to find away to get involved. I really appreciate all the information here! This pedal is completely amazing. I would even go as far as to say it is the core of my setup. I tinker, build pedals, mod amps and getting into guitar building as well. This is one of the few I have yet found away to unravel and clone. Compressors have always been important to me to keep from clipping my signal with in the pedal chain. Most compressors accomplish this, but always with a compromise. This pedal is the answer! It offers studio quality DBX technology in a pedal. It also features an on board charge pump to supply power at 18v from a 9v source. This is very important when applying an effect that is shaping sound. Headroom is incredible. The pedal has 3 controls. Some what limited however takes a different approach than most modern pedal compressors. Most use a sustain, level (passive ground) and occasionally attack. The cp9 utilizes threshold, ratio, and gain. All true circuitry, not a simple effect from changing a resistor like most comps. Threshold. Instead of the popular attack mod on most Ross style compressors the cp9 uses true threahold that allows you to dial in exactly when you want compression to kick in. It's very responsive and works very well. Instead of attack you can simply roll the threshold back to let you initial pick attack through. No other pedal truly does this!! Ratio. Many boutique pedal builders offer this and they aren't being completely honest. Most of them use a potentiometer to blend the signal with the effected signal. It just doesn't work very well Bc you can hear the clipped signal mixing with the compressed signal. This pedal however offers true ratio control 1:1 to infinity:1 and it's sounds amazing. No point on the spectrum avoided. Gain. In stead of the normal level controls associated with vol it has an actual gain stage. I was very impressed with this. With the doubled 18v supply it has a buttload of headroom. I'll stand by the statement that it reminds me of an active pickup. After squashing and limiting your signal you lose a LOT of volume. Not with this... You can actually use it as a clean boost. Very "transparent " (hate using that term). Most pedals use a grounded pot to ground the signal. Like what's in your guitar. The cp9 has 30 db+ to recover gain. There's also an indicating led on the face of the pedal that shows you visually how much and when your compressing your signal. It's a nice tool to help understand what the adjustments are doing. The only down side to the pedal has nothing to do with the units performance at all. With a retail price of 230$ US makes it seem some what unobtainable to the average bedroom guitarist. Like me. My opinion is that regardless of how incredible the pedal sounds, no pedal should cost that much. However, once you suck it up and dish it out I think that you'll wish you'd done it sooner. I promise you.. It's the closest to studio compression that your going to find. The squashed, dull, treble sucked tone associated with compressors can be negated. Unless that's what your after, it can do that as we'll. To sum it all up, I don't think this is the pedal for everyone. But if your tone obsessed and find yourself clipping every input you plug into than your going to want to try this. I rarely actually turn it off. Examples can be found on some of Adam d (kill switch engage) 'S clean work ( if you can find it lol). This pedal does not effect your tone at all. I give it a+++++.