Hello, after a long consideration I intend to buy the SC 805. I have upgraded all speakers of the Premium Sound line. Unfortunately you do not get the suitable amplifiers to the radio so often. How is that, if I want to connect any other amplifier to it? The radio has this round connection – is there there any suitable adapter or does someone know how this plug is used? And of course the question, which amplifier would fit optimally to the loudspeakers. Or does the radio already suffice from the power itself?