:

"The 1.3-ohm output impedance also allows the amplifier to listen to the room via acoustic feedback from the speakers. “The room to speaker to amplifier interaction provides a sense of believable ambience and acoustic space that is thoroughly realistic and quite enjoyable. Additionally, the transformer output impedance allows the signal to follow the impedance curve of the speaker system, delivering more voltage within an octave of its resonant frequency — providing a more satisfying low-end response,” says Carver."
http://www.cepro.com/article/print/b...h_new_audio_co