I have no idea of what height is ‘regular’ where you live. In UK modern homes most commonly are 2.4m, before that 2.7 or even 3m was not uncommon, and before that maybe 2-2.2m.
40cm from side walls is very close and is likely to have significant early reflections mixed with the main sound if not very absorbant or diffusing. Similarly if you are close to the wall behind you that is another source of significant early reflections.
This indeed is important - a fatiguing system is not a good system. The limitation should be your wish to listen, not heaving too much of it.
Given that you have predominantly hard surfaces I still think you need to look to the room, whether or not you change anything else. An overly reflective room with its confusion of early reflections is likely to be tiring on the brain - as well as making the sound less clear which you identified as your primary problem.
Given the cost of your system, if it were me I wouldn’t spend more on it without at least checking the rooms - and being prepared to spend maybe the equivalent of £2-£3k on treating it. Peanuts compared to the rest of the system. I suggest download REW software (which is free), buy a measuring microphone for the equivalent of about £100 or less secondhand (and recoverable on sale if not wanted further), do some measurements at the listening position, and submit to an expert in room treatment (in Uk some suppliers, e.g. GIK, provide a free service and can accept and interpret REW files, or post on the forum where a few people have experience and may be able to make suggestions.
Have a look at this thread: