There is a visible difference in size between the first launched amplifier, Kama Bay AMP Kro and the latest version of the AMP 2000:

The AMP Kro had in front only the power button, an amplification level dial, one amplified headphone jack connector and a mute button; AMP 2000 Rev. B comes with extra dials for adjusting the treble/bass levels, two decibel meters with light up when the device is turned on, one dial to select the input source, the fourth input jack and an USB power port (which, by the way, works perfectly to charge our favourite Apple device):

Both sides of the amplifier have black plastic covers on them, which are held with 4 screws:

In the back of the amp, we can find three audio inputs, left/right speaker connectors, DC-IN and USB power ports and a very useful analog meter switch from which we can choose input or output signal for the decibel meters:

On the bottom we can find preinstalled 4 stylish rubber feet:

In the case we would like to install the amplifier inside a spare 5.25'' bay, we need to remove the plastic covers from the laterals:

The left side also holds a sticker which covers one of the screws; if this sticker gets damaged, the warranty will be voided:

To see what is inside the amplifier, besides the two screws on each side, we also have to remove four from the top:

The interior of the amplifier is slightly modified compared to the first AMP 2000 revision, by including better capacitors and a larger transistor:

As the Kama AMP Kro, the AMP 2000 holds the same IC, a Stereo Digital Audio Power Amplifier; it has a maximum output power of 10W (for two channels) or 20W (for a single channel):

Some of the dials are placed on a daughterboard: