Both signals are linked internal to the corresponding second connector, so RCA -> RCA and TRS -> TSS and will not effect each other. For display, these both signals are internal mixed with selectable display channel (L / both / R).
A few years before SalTechips has done a research of the lifespan of IN-13 tubes which are a further development of the IN-9 but works in the same way. The conclusion was that the brightness ot the tubes drops within 14.7 years of continuous operation to 30%; these are more than 100,000 hrs!
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