Multi-mode audio amplifiers

An audio amplifier comprising:

• a mode controller configured to generate a control signal based on a bandwidth of an audio input signal, wherein the control signal has a first state in response to the bandwidth being a first bandwidth value and a second state in response to the bandwidth being a second bandwidth value, and wherein the second bandwidth value is greater than the first bandwidth value;
• and
• a variable-length finite impulse response (FIR) filter comprising
• a first fixed-length FIR filter configured to generate a first filtered signal based on a first digital audio signal, wherein the first digital audio signal is based on the audio input signal,
• a second fixed-length FIR filter configured to generate a second filtered signal based on the first digital audio signal, wherein a length of the second fixed-length FIR filter is greater than a length of the first fixed-length FIR filter, and
• an output module configured to
• select the first filtered signal in response to the control signal having the first state,
• select the second filtered signal in response to the control signal having the second state, and
• provide the selected one of the first filtered signal or the second filtered signal as an output signal;
• and
• an analog module configured to generate, based on the output signal, an amplified analog signal.