More details about the xj300fr and the technology behind it :

XJ300FR distinguishes itself from traditional power amplifiers by the unique class J power stage with interface velocity controlled output and Look-Ahead technology. This technology enables high power and continuous operation. With its micro form factor and flexible adjustment options XJ300fr can be adapted to almost any amplification task.

Advanced Technology
Xj300fr's brute force springs from the class J amplifier. The patented Class J technology manifests a quantum leap in amplifier technology. The revolutionary aspect of Class J is its ability to combine a high efficiency of 99% with extraordinary bass control. Class J is an evolution on PWM technology that combines advanced multi-level feedback with an intelligent controller. It modulates the supply voltage and output switching frequency in real time based on the frequency and amplitude content of the input signal. This added level of intelligence to the amplifier offers several obvious advantages such as increased thermal headroom through the amplifier's optimum energy use, dramatically improved bass response and dynamic power capabilities. This results in a harder audible impact that adds a drive to the sound normally experienced only at live concerts.


Crossover, Phase-shift and Volume
XJ300fr is equipped with variable electronic crossover which is infinitely adjustable from 40Hz to 175 Hz. The optimal setting depends on the connected subwoofer or tactile device. Xj300 also has a continuously variable phase adjustment function, where phase can be changed between 0 and 180 degrees.
The phase setting is optimally set by playing a 50Hz test tone and then rotating the phase adjustment knob until the maximum sound level is achieved at the listening position.
Volume adjustment makes it possible to gain match the subwoofer or the tactile unit with the rest of the system. It also allows the XJ300 to be used without a pre-regulated line signal.