I new we shouldn't have started watching Ghost Adventures and Dead Files on SciFi, and communicating with a ghost box. smile It is basically the clicking sound you hear when first turning on the 600 amp, it just keeps doing it.. I do have a different amp than the current 600v3 has in it.
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M80s-VP180-QS8s-EP600-2xEP350 Denon3808 Outlaw7700
M22-OWM22-VP100-Denon2805
Audio Nirvana