Acoustic amps are great if you're needing more volume for your acoustic guitar, want to amplify your vocals or have a range of instruments that you need a versatile system to play them all through. These little amps are essentially P.A systems in a small convenient package. When playing live they can often provide enough amplification for a small to medium size gig. Even if the venue has a PA system these amps can still act as a monitor to make sure you can hear yourself.
Choosing an amp mainly comes down to what you need from it. Here are a few questions that may help you find the perfect one for you.

How Many Inputs Do You Need?

Many acoustic amps will come with at least two inputs. Often these are combined 1/4" jack and XLR inputs so you can plug either into each channel. Some amps will have XLR on one channel and 1/4" on the other, so make sure it suits your needs. If you need more than two inputs you may need to look at PA systems. 
 
 

Do You Need Battery Power?

If you're looking to do street performances with your amp or you just often play in locations that power is an issue, we'd strongly recommend getting an amp with a built-in battery, such as the Fishman Loudbox Charge. The battery will charge when plugged into the mains and will last for a long time! Some amps require you to buy AAs or similar to power them. This works well if you can purchase a rechargeable battery set or don't mind having a stock of batteries on you.
 
 

Do You Want Effects?

Most amps will provide you with at least reverb as this is often fairly essential to making your instrument sound less dry and harsh. Some can even delve deeper with effects such as chorus, delays and more.
 
 

How Much Power Do You Need?

If you're using the amp for mainly your enjoyment or are in volume restricted environments, you'll probably find 20-30 watts will suit you fine.
40-100 watts will be required if you are playing in larger open spaces or smaller venues such as restaurants and pub gigs.
If you're playing alongside louder instruments such as drums or looking to play to a larger room or bigger crowds then look at 100-200 watt amps.