I’m a big two channel or 2.1 audio only guy. Kind of reluctant to use an AvR in my audio system set up. Having trouble lately with my Parasound may push me to get some
Room correction. I am going to try my current Marantz 1506 as a test to see what happens before selling and changing it all up.
What "trouble" are you having? You connected the sub to the actual sub output on the P5, then compared it to the Marantz by connecting the sub to the preamp output, which sends different voltage and decided that louder and warmer was better. You say the Marantz sounds warmer- is that a problem, or is one producing flatter response? Without testing, there's no way of knowing. You may prefer the Marantz, but it's likely that the Parasound is working normally. The "trouble" was caused by your comparison, possibly from a nagging, background thought from the volume control issue and now, you think you might want room correction.
If you moved your speakers for the first comparison, you can't be sure of what makes you think it's different because more than one thing changed. Changing something else in addition might not help- correct speaker placement in the room is a physical thing, not a design element nor should it be dictated by lifestyle, but they're generally the most common reason for where speakers end up. That leads to people designing equalization systems that don't universally cure all problems.
I would start by finding the best place for the speakers and come up with a way to make it repeatable if leaving there would cause problems with traffic flow, WAF, etc. That way, you can move them out of the way when they're not being used. Once that is done, compare the equipment and make your decision, but connect the sub correctly OR similarly- again, the sub out and pre out levels are different and that makes it impossible to say "all things being equal".
Bass level causes us to perceive the sound as 'louder', 'more dynamic' and 'more realistic' when one speaker system or setup has it and another doesn't. Loudness is measurable objectively, intensity is the perception that it may be louder. Listening tests aren't objective, so the variables need to be controlled and made smaller in order to make it unbiased.
All of this said, a bit of room correction can make a big difference, but it needs to be done right.
BTW- which SVS sub do you have? I was looking at their site and the DSP controlled by the app interests me.