The SP-9000 enclosure features two 4" (100 mm) speakers, affording independent audio paths for the Main and Sub VFO audio output; the left speaker puts out Main VFO audio, while the right speaker yields Sub VFO audio, and a front panel switch also allows you to combine the audio signals from both receivers for mixed distribution from the two combined speakers. This produces an effective aperture of 8" (200 mm), for outstanding tonal quality! The audio filters provide three steps of high-cut (2400/100/700 Hz) and two steps of low-cut filtering (500/300 Hz), and each audio path (Main/Sub) may be filtered independently, allowing you to experiment with optimum settings in a "Diversity" dual reception filtering mode. You also get individual mute switches, useful for dual receive operation.
Twin headphone jacks are provided on the front panel of the SP-9000, providing monitoring of both VFOs A and B.