From: johnwilliamson@btinternet.com   
      
   On 26/12/2025 15:43, Tobiah wrote:   
   > It's actually a POA-2200.  I found a block diagram:   
   >   
   >   https://imgur.com/a/ivhcMCR   
   >   
   Interesting.Imgur won't let me see that as I am in the UK. I suspect   
   that our online safety law has come into play. Amplifier porn. ;-0   
      
   > Not sure why the low-pass filter on the CD input.   
   > Other than that, using both inputs would be like   
   > using a 'Y' cable, which I understand is a no-no.   
   >   
   I'd expect a low cut filter on the normal input to reduce rumble.   
      
   The block diagram in the service manual shows a hi cut filter on the CD   
   input.   
      
   (a 7.5 k Ohm resistor in series with a 270 pf capacitor which is in   
   parallel with a 50 K Ohm potentiometer.   
      
   A quick check shows it may be designed to stop any clock frequency   
   leakage from the DAC, as the -3dB point is above 78 kHz.   
      
      
      
      
   --   
   Tciao for Now!   
      
   John.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)