help! power amp won't work with two input sources are connected

[derekchan]

my avr mrx740 output front channel to this power amp mca225 via rca port
the xlr port of power amp are connected with xlr output port of mcintosh c8 pre amp

the power amp works well while as a power amp of av receiver.
it will has issue when i unplug the av receiver,use mcintosh pre amp to output streamer source to power amp
there is no sound if use xlr input of power amp

until you unplug the rca input cable of power amp,the speaker can play sound from xlr output of mcintosh

i shared the same speaker with av receiver and mcintosh, because the power amp only can paired with one speaker

 

[Ruediger]

It seems to use auto-sensing and switches to that input.

Tried disconnecting RCA and testing with XLR only?

 

[derekchan]

It seems to use auto-sensing and switches to that input.

Tried disconnecting RCA and testing with XLR only?

it works when disconnect rca and connect xlr only
but i want to hook up two input for av receiver for multi channel and two channel for mcintosh pre amp

 

[Redacted]

"power amp won't work with two input sources are connected"
"i want to hook up two input for av receiver for multi channel and two channel for mcintosh pre amp"

Doesn't make sense to me.
Draw a pic of how it's all connected up, take a pic of it and post it here.

 

[Ruediger]

it works when disconnect rca and connect xlr only
but i want to hook up two input for av receiver for multi channel and two channel for mcintosh pre amp

You could use a source selector and just use one input on the power amp.

 

[derekchan]

You could use a source selector and just use one input on the power amp.

what hifi brand of source selector is good?
i only have single pair 4309 speaker with two pre amp mrx740 and mcintosh c8, but only one power amp mca225 to drive 4309

 

[Roland68]

what hifi brand of source selector is good?
i only have single pair 4309 speaker with two pre amp mrx740 and mcintosh c8, but only one power amp mca225 to drive 4309

The MCA225 does not have a selector switch to choose between the RCA and XLR inputs.
The manufacturer did not intend for RCA and XLR inputs to be connected simultaneously.

You would actually need two switching boxes—one for RCA and one for XLR—to disconnect the input not currently in use.

 

[Ruediger]

what hifi brand of source selector is good?
i only have single pair 4309 speaker with two pre amp mrx740 and mcintosh c8, but only one power amp mca225 to drive 4309

Audiophonics has some selector boxes that can help you with RCA and XLR.