My Fender champion 20 guitar amp is constantly buzzing every time I plug in my Fender Squire Stratocaster. My whole setup is very new and very basic; I haven't got any batteries or pedals. Acoustic seems to work fine when plugged in so I'm not entirely sure if it's the amp or the lead or the guitar. Please try to get in touch A S A P because it is driving me crazy.
Since the acoustic sounds fine it's not the amp. It's the single coil pickups on the strat picking up noise from the electrical system in your house. It's very common. The kinds of pickups used in acoustic guitars don't have this problem. Try moving to a different area of your house and/or turning off all lights and other electrical equipment.
I would say, firstly, that the question is a bit vague. I'm not sure if the buzzing is intermittent, varies with control settings or the proximity of the guitar to the amp or other sundry electronic devices. I also don't know if this is a new phenomenon for the OP or something that has always happened. A new buzz would suggest to me that the amp has maybe gone tech, at which point I would take it to a qualified repairer. Even small amps have power-smoothing capacitors that can store lethal charge, whilst looking fairly innocuous on the circuit board.
I disagree with the notion that cheap Chinese components are somehow more noisy than anything else. The cleanest example of a pre-CBS Fender Stratocaster will still have unshielded cavities, unshielded single coil pickups and no coaxial or other form of shielded wiring in the cavities.
Shielding a guitar can cut down on electrostatic interference (ESI) if carefully and methodically implemented. ESI is simply generated in the presence of AC voltage. Get a shielding job wrong and your guitar can still be noisy however. Single coil pickups are good at capturing electromagnetic interference (EMI), which is generated by electricity doing things, such as a dimmer switch, CRT monitor, washing machine motor etc. EMI cannot be eliminated through shielding, but can be eliminated with 'dummy coils', which are unmagnetised single coil pickups wound 180 degrees out of phase with the 'seeing' pickup coil. You could make one simply by taking a cheap Strat pickup and knocking the ceramic magnet off the back. A lot of Strats utilise a reverse-wound middle pickup (allowing positions 2 and 4 to hum cancel). At best 2 of your Strat's pickups will benefit from a dummy coil with the remaining middle pickup's noise being exacerbated by it, as you are effectively summing the noise picked up by each coil.
Noiseless pickups are an option, and some manufacturers have gone to great lengths to come up with pickups that retain the 'sparkle' of single coils but without the hum. The less creative, such as Fender, have simply glued a dummy coil to the bottom of each pickup and then suggest you increase the value of the potentiometers in your guitar to compensate for the additional loading. Kinman use a much more technically involved design, but a set of their pickups will cost more than the OP probably paid for their entire rig. There is the Suhr backplate system, which is a complex and well-engineered dummy coil solution, but again you will pay a lot for the privilege.
Lifting the ground on any amplifier, even a cheap low-watt solid state practice amp, is reckless advice and not the sort of habit any musician should be getting into; like a mechanic advising that you under-inflate the tyres on one side of your car to compensate for the steering being out of alignment. The underlying issue with OP's amp or guitar isn't effectively dealt with, and you are simply using a risky kludge to mask the issue.
Before you go monkeying with the inner workings of your amp...double check your amp settings...they are known to cause "distortion", lol. If the settings are not helping, most likely you have a ground issue. Did you introduce any new electronics or appliances that may be sharing the same circuit? Or change the config of the signal path?
Pick up a ground lifter...might get a few actually. Three prongs go in...two go out the other side...no ground transfer. If this doesnt fix the problem you have spent less than $1 and you have ground lifters...which will fix the majority of mysterious hums and buzzes that pop up. You can get at just about any hardware or electrical supply store, as well as lowes or home depot