In response, let me say first that this is a relatively 'new' model not the AC-30. As the label indicates it a ''Vox Acoustic'. It has three settings STANDBY(power off) ON(power on and no effect) and FX (acoustic effect on). It operates on 2 AAA batteries.
The effect is voiced to bring out the high frequencies of acoustic guitar or electric as well depending on the BLEND and TONE control settings. The promotion indicates "it adds sparkle". There is a BLEND control varies the effect. The TONE controls seems to only be adjustable when in the FX mode. In the ON mode the eq sound is more or less 'flat'. The VOLUME control controls the overall level.
There is also an 1/8 input jack for an MP3, CD, Drums, or other effects if desired and the level is controlled at the source rather than the VOX volume. If you want delay or reverb then plug it into your battery powered reverb/delay box output and use a short guitar cable on the input from the guitar.
Comparing the sound to a regular amp speaker is subjective because it depends on what headphone is used. There is no reverb, delay, distortion, on this model only the acoustic FX and BLEND. I experimented with my Gibson and Gretsch CG, the CGP, Gibson CE, and Taylor acoustic steel string and it sounded good on all these after I adjusted for each.
Like everything else there is a trade-off for a full size amp, and it is mostly for private listening or for the convenience of traveling.
http://www.voxamps.com/amplug/