NAD T751 multichannel board/ very low output

I've been trying to trace an issue with my NAD t751.
1. Extremely low volume output on both left and right channels
2. No output when surround mode selected.
3. Doesn't matter if headphones or speakers
4. Doesn't matter which input.

I've bought an oscilloscope and I THINK I've traced it to the multichannel board. Audio goes from inputs to this board, then sent to the amplifier boards.
I get a signal from my freq generator to the input of the "m62447sp" IC.
It seems that the output pins of this chip are dropping the signal. Is this how it's supposed to operate or should the volume be increased and maintain waveform?
I'm not sure if I've just found the issue or if I'm misunderstanding this IC.
See attached docs.
 

Attachments

  • M62447SP.PDF
    M62447SP.PDF
    85.2 KB · Views: 24
  • t_751.pdf
    t_751.pdf
    5.6 MB · Views: 111
  • multichannelT751.pdf
    multichannelT751.pdf
    274.1 KB · Views: 20
  • 20250316_222459.jpg
    20250316_222459.jpg
    551.8 KB · Views: 19
  • 20250316_222543.jpg
    20250316_222543.jpg
    496.8 KB · Views: 22