Sound — 9
I've played a Washburn Telecaster an B.C. Rich Beast (bronze) on it and they both sound pretty nice. When the distortion is up, it will buzz on the Telecaster, but that's because of the single coil pickups. The buzz isn't too bad as long as you stay away from equipment like a computer monitor or a TV. When in clean, it sounds pretty good. It's very basic, but it's not too bad. The distortion is alright for a 4 watt $30 amp. It gets the job done if you can't use anything else, though it sounds kind of muddy if the volume is all the way up. You can also get 2 completely different sounds out of the distortion. One which is pretty crunchy, and another one that will remind you of your basic rock kind of sound. A lot of you wonder about how loud these little mini amps can get. I'm not sure about the other mini amps, but this one is definitely loud enough to piss off your parents.
Overall Impression — 8
This amp really surprised me when I first played it. I'm not disappointed at all, and I can definitely recommend it to someone who is too broke to get a better practice amp, such as a Roland MicroCube. But hey, if you have the money, you're not missing out on much by passing this deal up.
Reliability & Durability — 10
I've had this thing for a few months and it hasn't had any technical problems, and while the body of the amp itself is made of plastic, it is pretty tough. I've dropped it from about 4 or 5 ft and it still plays and sounds just as good as it did when I first got it.
Features — 8
The Johnson JA-004 is a mini amp which is about the size of an average person's hand, give or take. This thing has 4 watts in it. It has an AC adaptor input, headphone input, and of course the input for the guitar. It features a volume knob, tone knob, and an overdrive knob. Overall, if you're short on money, want something small and portable, and/or just curious, this isn't a bad choice at all. Its features are pretty good quality for how cheap the thing is, and so far I haven't run into any problems. You can also power it by one 9V battery. It doesn't last too long though. Maybe a couple hours before it starts effecting the sound drastically.