That is awesome! I’m glad the A21 is working out. One thing you may try is to do critical listening with “Pure Direct” turned on and then turned off. I had a scenario with a Yamaha receiver in which the Pure Direct mode sounded worse. It was just too solid-state sounding and bright/harsh. I think turning Pure Direct “off” basically routed the audio signal through another set of op amps, which further smoothed out the sound. I’m not saying this will work the same way in your situation – everything is dependent on components used and system synergy, but it’s something you can try in addition to turning off Audyssey.
Here’s another thing I have found. Digital audio that is played using HDMI cable as the source is not as good as using a digital COAX cable. It just does not sound as good. If you have not already done this, I would recommend you at least get a Beldon 1694A digital cable for each source (bluray, satellite, etc.) you have that can do a digital coax output.
https://www.bluejeanscable.com/store/digital-audio/index.htm
I have found these Beldon cables work excellent and are better than several other cables. At $20 each for a 6 foot cable, it’s an excellent buy. I always recommend minimum 5-6 foot digital cables to prevent short cable signal reflections. You would have to pay $120-200 to get to the next level, such as Audioquest Cinnamon/Carbon or DH Labs D-750 cables. These more expensive cables use silver-plated conductors which are better for digital pulse transmissions.
I have found that there are only two scenarios which require that you send digital audio over HDMI cable:
1. Sources that require Dolby Digital Plus (such as streaming services from Netflix / Amazon / Etc.). For some reason, you cannot send Dolby Digital Plus over normal coax.
2. Bluray movies that use the bluray high resolution audio formats, either DTS-MA HD or Dolby TrueHD. The only way you can play DTS-MA/TrueHD is over HDMI.
For normal old Dolby Digital and DTS, and even 2-channel PCM (which you would get when doing normal audio streaming from Pandora, CDs, etc.), it just sounds better to send this over digital coax cable instead of using HDMI for the digital audio. You would still need to use the HDMI cable for video.
Since you would potentially need both HDMI and coax digital audio from your Samsung Bluray player, you could try doing setting up your inputs on the Marantz like this:
[HDMI] [DIGITAL] [COMP]
BD HDMI1 None None
DVD HDMI1 Coax1 None
I’m not sure if the Marantz will allow you to use the HDMI1 input for multiple sources, but you can try it out. Then select “BD” source when playing bluray movies that use DTS-MA or TrueHD audio. Select “DVD” when playing anything else (movies with normal DD/DTS, CDs, Pandora, etc.).
It's a very cheap way to potentially increase the end result sound quality.