Any guitarist, especially electric guitarist, who lives with other people knows what I mean.
Types of Amps
Guitar practice amps generally fall into 2 different categories. One type is solid state with features designed to make it "spouse/neighbor" friendly. The other type is tube and follows the example of the Fender Champ. Let's look at each.
The first type usually run 10-15 watts. Common features are volume and gain controls, a headphone jack and CD input. Some manufacturers are starting to add digital effects. The downside to many of these amps are that, through the speaker, they have a "tinny" sound. The upside is bypassing the speaker and having CD access for play along or learning purposes.
The second type is the current generation of small tube amps. Small, low powered amps were the norm during the 1930's when electric guitars were invented. Fender began making small practice amps like the Champ in the mid-late 1940's. These fell out of popularity for awhile but have been re-introduced in recent years.
Most of these small tube guitar practice amps feature single input and very simple tone controls. They rarely have a headphone jack. The advantage of them is tone. They are far more likely to sound like a classic Fender guitar amp than any modeling amp ever will.
Which Amp For You?
Only you can decide which amp is right for you. There are pros and cons to each, of course. Fingerstyle players will have a different set of needs than other guitarists.
Most fingerstyle guitarists prefer a fairly clean sound. The most commonly used effects will be delay and reverb. Also, as a stand alone, solo instrumentalist, they'll probably prefer the warmer, fuller sound that is associated with tube amps. Of course, on the tube amp there are rarely onboard effects. An outboard stompbox or effects processor would have to be used.
This brings us to the solid state amps. They frequently have onboard effects. In the past there has been a trade off with the drier sound that a solid state amp can have.
Some guitar practice amps actually have a tube pre-amp. You get the cheaper power of solid state with the warmth of a tube.
So far, we've just talked about guitar practice amps for electric guitarists. Using a practice amp can help acoustic guitarists too.
If you only gig occasionally, you may not be used to what your acoustic sounds like when it's amplified. It's a little odd to have your guitar's sound seem to come out of a box on the floor and not the soundhole.
An acoustic guitar amp will make all of the pretty sounds of your guitar louder. It will also make all of the ugly sounds, (finger noise, etc.) louder as well. It can be startling if you're not used to it. Throw in all of the other variables that come with bread-and-butter gigs like playing in restaurants, and it can unsettling.
While acoustic guitar practice amps aren't as common as electric amps they do exist. You can use headphones on a little amp and work on cleaning up your acoustic-electric guitar technique.
A guitar practice amp will never replace a vintage guitar amp. But you still might find that it has a place in your gear lineup.