From: toby@tobiah.org   
      
   It's actually a POA-2200.  I found a block diagram:   
      
      https://imgur.com/a/ivhcMCR   
      
   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.   
      
   Maybe the filter gives enough isolation that it   
   would still be possible?  Or perhaps there is more   
   circuitry involved that does not show up on this   
   diagram that would make it ok.   
      
   I'm also not sure how to set the input level knob.   
   I just have them at half-way right now.  If it controls   
   gain, I would think that the minimum level that gives   
   me the output I need would be best.   
      
   I'm curious though, if I were using this amp with   
   a CD player, how would I control the volume?  As I   
   said, there is only power and speaker A/B on the front.   
   Surely they don't expect one to reach around the back   
   and adjust both gain knobs.   
      
      
      
   Toby   
      
   On 12/26/25 07:09, Tobiah wrote:   
   > I have a Denon POA-220 stereo amplifier that I use   
   > to monitor an audio interface when running Windows.   
   > This interface does not work under Linux, But I have   
   > a Scarlet 2i2 that does.  I tried using a Radio Shack   
   > stereo switch to change the amplifier source between   
   > the two interfaces, but it introduced noise.   
   >   
   > So I noticed that the amp has two RCA inputs for each   
   > channel:   
   >   
   >    https://tinyurl.com/mrxzrwuf   
   > one marked "CD" and the other "NORMAL".  I'm tempted   
   > to use these to connect both interfaces at once, but   
   > something tells me that may not be a great idea.  There   
   > are no input switches on the amp.  The only controls   
   > are power, and speaker A/B switches.   
   >   
   > My main interface is a Presonus 1810, with the older   
   > USB connection.  It seems that the USB-C version is   
   > supported by Linux, but I can't get my version to work,   
   > although I do see some Alsa devices (but not the outputs)   
   > in the mixer.   
   >   
   >   
   > Toby   
      
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