Using a wahs with fuzz pedals is like trying to tame two wild beasts at once; they can make a lot of noise when used alone, but when put together - things can get truly out of control!
Some people love running a wah into a fuzz, as it gives them that iconic soaring Hendrix sound. But most of time, it just sounds strange. So, why not run a wah pedal after a fuzz pedal? Well, that can sound even worse; exaggerating the wah sound and producing a harsh, chaotic tone that will deafen your audience. This is because a wah has a fairly high output impedance, whereas a fuzz has a far lower input impedance. This means that you just can’t get the most out of your wah, as its range is hindered by the fuzz.
So, this is where buffer pedals may come in handy. If you run a wah into a buffer and then that into a fuzz, this can resolve the problem and give a more natural and usable tone. Basically, the buffer will convert the high impedance signal from the wah back into a lower impedance, which the fuzz prefers in this context. You can buy specialised buffer units, such as the TC Electronic Bonafide Buffer or JHS Little Black Buffer to do this.
If you try this method then it’s important to find a way to turn off the buffer when you don’t require the wah, so that you can get the best out of the fuzz normally. A true-bypass wah with a built-in buffer that is engaged only when you turn on the pedal is one solution, although they’re hard to come by. The best solution is to run your pedals though a switching system like the Boss ES-8 or ES-5 units, where you can isolate and rearrange the order of your pedals on-the-fly. They’re expensive, but they make your setup more tweakable so that you can experiment and overcome signal chain problems.