From: geoff@nospamgeoffwood.org   
      
   On 27/12/2025 4:43 am, Tobiah wrote:   
   > 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   
   >   
      
   Curious as to how a simple mechanical switch (slide ?) could 'introduce   
   noise'.  Unless close to a powerful electro-magnetic field such as an   
   external power supply, or close mains cabling.   
      
   --   
   geoff   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)