Currently there are three levels of the Amplitube mobile applications: Free, LE at $2.99 and the Full version at $19.99. The Full version has five amp models: clean, crunch, lead, metal, and bass with full tone and drive controls. There are also 11 stompboxes including delay, flanger, phaser, overdrive, distortion, envelop filter, wah, fuzz, octaver, chorus, noise filter and five speaker cabinets with 1x12, 2x12, A & B 4x12s and 1x15-inch speakers.

All app versions have both dynamic and condenser mic choices, a good chromatic digital tuner and a metronome with tap tempo. You can import backing track to play along with and save and recall up to 36 presets on the fly.

The lipstick-sized iRig interface adapter has the proper input impedance jack for your instrument (but it also works with line level signal sources such as synthesizers, keyboards or mixers) and a short pigtail connects it to the ear phone/mic jack of your iPhone/iPad/iPad Touch. The iRig's stereo 1/8-inch mini-jack connector output jack drives your ear buds or connects to your guitar amp or recording system by way of an (not included) adapter cable.

After installing the Free version into my 16GB 3GS iPhone (OS 4.0.1), I found the output level more than loud enough for my professional in-ear monitors and plenty to drive my mic-pre DI inputs connected to my Pro Tools HD 192 interface.

Every time you launch the IK software app, you'll have to immediately deselect the No Feedback option in the Setup page or else the left and right outputs are phase reversed (purposely) to cancel out possible feedback when connected to headphones or ear buds. The software comes up with a default amp set up so select one of your saved presets as it does not remember your last used set up. For safety's sake, I got into the habit of "cinching" both the iRig interface and iPhone under my guitar amp's handle strap so they would stay put when I plug in.

I liked the tap tempo metronome feature for practicing using ear buds and the five different cabinet models and two mic choices available produce loads of different and big sonic choices. BPM sync is very handy when using the Delay pedal and storing presets is easy to do on the iPhone's touch screen. Actually all the various controls on the amp models and stomp boxes are easy to manipulate because, when touched, the rotary knobs' actions are duplicated on a larger touch fader that indicates a numerical value or (in the case of the delay) time in milliseconds or in musical note values if BPM Sync is in play.

I found the same super low-latency (when switched to Ultra-Low) as when using Amplitube 3 in my Pro Tools rig. Even with this Free version, there are plenty of good sounds but I plan on getting the Full version soon. You can build up your Free or LE versions by downloading and buying any of the eight additional stomp pedals at $2.99 and/or the four amp modules that include speaker cabs at $4.99 each.