Please help. Why would higher power amp require gain? Marantz/Adcom
The only caveat being that the rear channels have less information than the front channels, and may be closer to the seating position. Both items would serve to reduce demand on those rear channel outputs over having the 555 amp driving front channels. But perhaps the difference would be too small to worry about. |
One other thing. Any amplifier requires a certain voltage to achieve unity power. The 555 can do 200 wpc, but it requires around 1.7 volts on its input rca jacks to do this. At least the current 555SE needs 1.7 volts, perhaps the old 555 needs a different spec. So the question is, what is the max voltage of the pre outs on the Marantz? Most mid level AVR's do 1 volt max, which will not let the Adcom get to 200 wpc. I believe that many multi channel amp manufacturers take this into account and achieve unity power at 1 volt, not sure about the GFA 7500. |
I found an old review of the 555 II. It needed 1.75 volts at the inputs to achieve full power. Another old review of the 7500 says it needed 1.14 volts to hit 150 wpc, so that should be fine for the Marantz. http://www.users.interport.net/a/d/adcom/gfa7500.html https://www.kenrockwell.com/audio/adcom/gfa-555-ii.htm The pertinent information is buried in these links, hope this helps. |
My knowledge on this is by no way exhaustive, but it’s a little concerning to me that Audyssey is having to run the left and right so hot to compensate for the input sensitivity of the 555. it might be better to have the 555 on the rear channels where less demand will be put on the marantz preout section. Others may have additional thoughts. |
