A Naim departure?! I'd prefer not... amplifier advice pls

Hi @Mulberry Imbalance is identically presented on both the SN3s I’ve had. Tests done already are:

  1. Balance knob travel tested. Equal left to right extremes.
  2. Switch speaker cable connection at amp end (channel imbalance switches to right as right speaker is connected to left SN3 output). Rules out speakers and room.
  3. Switch actual speaker cables left to right. Channel imbalance remains on left.
  4. DIN and RCA from NDX2 used. Same on both.
  5. Different, less sensitive speakers used. Same.
  6. Input connector switched from Stream. Same.
  7. Different source used. Same.
  8. Volume attenuator replaced. Same.
  9. SN3 used in AV bypass mode. Same. This one is the most telling as it indicates an issue with the power amp stage.