I'm 58 and just starting to learn guitar (about 50 years after i told my parents I wanted to learn electric guitar). I bought a CODE50 because I didn't want to buy a "starter" amp now and then "need" to buy a more powerful one later. 

The first thing I did was to put on my acoustic-electric and then, with the sound hole about a foot away from the speaker, turn the CODE50 on. SCREACH!!! Okay, so point the speaker away from the piezo pickup and try a lower Master setting. Even with the speaker and soundhole pointing in different directions, I had to keep the volume way down to avoid feedback in my little home office.

Next the Epiphone Les Paul. Boy, oh boy, even with no soundhole and turning my back to the CODE50 while it was pointed away, my electric picked up the vibes off the walls and seemed close to feedback with louder presets.

Finally, listening to acoustic guitar and harmonica blues from iTunes over USB (Paul Richell & Annie Raines, Moving to the Country), there was no feedback issue, but this thing is so damned LOUD I had to keep the Master at about 2 on preset 00 to listen comfortably.

I will never need more power than a CODE50 in my house.