which means these functions?
All GT models feature Boston's exclusive DualMode™ technology, which permits safe operation into speaker loads as low as 1 ohm (stereo) or 2 ohms (bridged mono), thus increasing amplifier flexibility and all models can drive subwoofers or full-range components with equal ease. The new amplifiers also feature Boston's Q-Tune™ delivering user-adjustable "Q" for each amplifier's highpass crossover filter. This provides substantial system "tweaking" power, allowing the user to enhance the bass impact from the front channels without overloading the speakers. With wide-ranging input sensitivity (to 7.5V), compatibility is extended to the widest possible range of head units, factory adaptors, and system preamps. Rounding off the feature set are adjustable 12dB/octave highpass and selectable 12/24dB/octave lowpass crossovers and for further flexibility, these can be combined for bandpass operation.
Boston Acoustics GT Line of Car Audio Amplifiers