Russound P125 Owner's Manual

The Russound P125 is 2-channel dual source power amplifier with auto-

source switching. Features Primary and Secondary audio line inputs with a loop 
out to another zone, receiver, or device from the secondary source. A speaker-
level input can be connected and assigned as either the primary or secondary 
source. This amplifier can be used for power upgrades in zones for large speaker 
selector or volume control systems.

The P125 is rated at 125 watts per channel into 4 ohms, and 80 watts into 

8 ohms. Output channel incorporates robust protection circuitry for reliability 
and safety under extreme circumstances. 

With the Stereo/Bridge Mono switch in the Bridge Mono position, channels 

are combined for a higher powered mono output. In Bridge mode the P125 is 
rated at 250 watts of power into a single 8 ohm load.   

The 12V Trigger In/Out allows each amplifier to be activated by other devices  

or to activate other electronics via a 3.5 mm mini phone plug cable, with 100mA 
current capability.

The P125 is designed with special circuitry to safeguard the amplifier under 

a thermal overload condition. Thermal protection mode will only engage 
when the unit has been run at high volume for extended periods of time 
without adequate ventilation and/or when speaker impedances are below the 
minimum levels for the amplifier. In thermal protection mode the amplifier will 
automatically stop output. If this fault occurs, turn off the amplifier, and check 
that the speaker impedance rating is above the minimum rating. Also check for 
adequate ventilation around the amplifier and make adjustments if necessary. 
Once the unit has cooled to safe operating temperatures, the amplifier may be 
powered back on.

Special circuitry has been designed into the amplifier to safeguard under a 

short-circuit condition. A faulty speaker can also cause a short circuit condition. 
If this fault condition occurs, turn off the amplifier and check speakers for short 
circuit conditions when appropriate. The amplifier power must be cycled for 
the unit to return to normal operation.

The P125 amplifier can be placed on a shelf in an equipment rack or on a table 

or cabinet. Be sure to follow the required clearances shown on page 3 to allow 
for ventilation and heat dissipation. 

On the front panel of the P125 amplifier is the power button plus speaker 

selector, balance and volume adjustment. 

Power - the front panel switch will manually switch the power on or off.

Speaker selector - select speaker pair A (main) or speaker pair B (auxiliary) for 

audio output. You can use speakers A and B together, as long as the speakers 
are at a minimum 8-ohm impedance.

Power LED indicator - RED = ON, RED = Standby. AMBER = 12V Trigger 

switched on.

Balance - adjust speaker output balance between right and left channels. The 

default setting is at center.

Volume - adjust the speaker output volume. If using Bridged mode, set the 

volume at minimum, then adjust to the desired level.

The P125 amplifier can be turned on manually or automatically by setting a 

switch on the rear panel. For manual power on or off, set the switch to Normal 
and press the Power button on the front panel. For automatic power on, set 
the switch to Auto On. When music is sensed on any input, the amplifier's 
signal sensing sends a command for it to power on. Once the signal ends, the 
amplifier turns off in about 4 minutes. To turn the amplifier on remotely, set 
the switch to  Trigger and connect a 3.5mm phone plug remote triggering wire 
from the device to the 12V Trigger In on the amplifier.  

NOTE: The front panel Power button must be in the "On" position for the 12V 

trigger and Auto On features to work.     

When connecting speakers to the amplifiers, use a minimum 16 gauge and 

maximum 12 gauge stranded copper cable. Avoid leaving stray strands and 
keep polarity consistent.