Couple thoughts you may want to add into your equation. What source/s are you experiencing these issues with….Dac, phono? OR is everything equally less than acceptable in sound? Do you have any other speakers that you could hook up to provide some type of comparison? Has this combination ever sounded good to you? You may want to try some type of sound demo tracks and see how they sound on your system. Do you have a dealer where you could demo another integrated to see if that improves your sound? How old are your speakers, and do you have subwoofers? I would start with all the basics first, straight from the power cord, to interconnects and speaker wire. If all that checks out then you may just have two components that are not a good match. I had a similar situation with my system where I was running McIntosh mono blocks with Martin Logan electro stats and the Martin Logan’s needed an power supply that went down to 0 ohms but the McIntosh was not capable of delivering that so I never got the full experience of my system.
Hope this helps and let us know how you make out!
Good Luck rlross3!!