Right Channel dropped out Bryston BP-26P (upgraded from BP-25P)

SOIX. Yes PA works fine with Adcom GFA-1
OLDHVYMEC.  First. I’m listening to system with Adcom in system. All sounds fine. Right channel working fine. Bryston uses a magnetic master circuit breaker switch on rear of amp. It didn’t trip but I did reset it. No difference. I even connected my PA to Bryston amp via single ended inputs to see if there was a problem with the balanced outputs. No Go. I did send a text to Bryston tech waiting for a response 

The balance control issue is driving me nuts!  It doesn’t make any sense. But I’m listening to music now. So I’ll wait for Bryston’s response. I’m sure it’ll go back. 17 years left on warranty!

Appreciate everyone’s comments and suggestions 

dean

Look into the RCA and XLR connector jacks with a bright flashlight to make sure nothing is stuck in there. To me this sounds like the right channel is shorted to ground. If nothing is in there, then the unit has to go back to the mothership.

The balance control issue is driving me nuts! It doesn’t make any sense.

However, balance ctrl in center, I have left channel output in both speakers. Balance Ctrl fully to right channel...nothing.

If the Bryston 4B cubed is set to bridged mode, the 4B cubed will disconnect Channel 2 input and only take the Channel 1 input signal and send the signal to both amplifier channel. Channel 1 will amplify the signal in phase and Channel 2 will amplify the same signal but out-of-phase.
If OP connect the preamp left channel output to 4B cubed Channel 1 input and connect the preamp right channel output to 4B cubed Channel 2 input, then OP will hear both speaker playing left channel signal from the preamp, if OP listen carefully, he will notice the bass is reduced due to one of the speaker is playing out-of-phase ( opposite in polarity). That explains why when balance ctrl in center, OP had left channel output in both speakers. Balance Ctrl fully to right channel ... nothing. And that’s the reason I ask OP what is the mode setting.
However, OP had confirm the mode switch on 4B cubed was set to individual and not bridged, therefore I suspect the mode function on the 4B cubed is not working correctly.

https://img.canuckaudiomart.com/uploads/large/1913106-3942baca-bryston-4b-cubed-silver-face-with-han...

Imhififan. That makes sense to me. I boxed unit yesterday to send back to Bryston.  I’m awaiting their response. Thanks much

IMHIFIFAN. Meaculpa. After reading your last post, I unboxed the amp and………yup switch was in MONO!  And I’m sure I checked that.  Reinstalled the amp in my system, quadruple checked ALL the connections and switches, powered up the system and It worked perfectly.  Thanks for your comment and advise and link.
Human Error prevails. 
Shut everything down and went to Capital Audio Fest to unwind.