A headphone amp is a great little gadget for guitarists. About the size of a pack of cigarettes, a headphone amp allows you to just plug in an electric guitar and a set of headphones, and switch it on. Then crank up the volume because no one can hear but you! A headphone amp is ideal for practicing anytime, night or day, without disturbing friends, family, roommates or neighbors.

Aside from simple amplification of the guitar signal, a headphone amp can also be a miniaturized portable studio with effects processor, amp modeling and rhythm machine. Analog and digital effects processors can emulate everything from heavy distortion to hard-core crunch, chorus, echo, funk and more. See how the effects sound through a variety of digital amps, from the Classic Fender tube amp of the 60s to Marshall, Vox and others. A built-in rhythm machine can provide several different rhythm patterns to serve as drummer. Then, with the press of a button, choose your venue and the headphone amp can place your drums, guitar and chosen amp in a club, large arena or other acoustic environment.

One of the nicest features of a headphone amp is the ability to learn new songs by using the auxiliary line in to patch in a radio, CD or MP3 player. Download tab from the Internet if desired, then work it out as you play along. If you prefer working out the song yourself, some models include a feature that records up to 30-seconds of a song, then slows it down in steps to 1/4 speed without changing the pitch, ideal for learning licks.

A headphone amp that does not include a drum machine often includes a click track metronome or sampled snare drum kit to provide a backbeat. Beats-per-minute or tempo is always adjustable. This is a great tool for sharpening your timing.

Another handy feature included with most models is a built-in digital guitar tuner. LED lights indicate flat, sharp or true tuning for each note. Some models are also designed with a protruding jack that slides right into the guitar itself, eliminating the need for a guitar cord.

A headphone amp is a must-have item for virtually any guitarist. The flexibility it affords to play anywhere —- including the back seat of a car, the middle of a forest or the middle of campus —- coupled with the ability to play any time of day or night is reason enough to have it in the gig bag. The jam-along feature seals the deal.

The price of a headphone amp can range from US$30 for a basic model to about US$100 for a high-end model, and they are available everywhere guitars are sold. One manufacturer has combined a 4-track digital recorder with headphone amp, creating a palmtop recording studio that includes programmable bass and drum machines. This model sells for about US$199. Shop for the features you prefer and, if shopping online, look at customer reviews to help you decide which model is best suited to your needs. In most cases, bass guitars have their own designated models.