I think this is a really interesting problem and one which I have also experienced in the past.
What you have are some highly revealing speakers and a sub which are highlighting problems in the audio signal, upstream.
You don’t need to spend very much to fix this and i don’t believe buying a less revealing speaker is the way to go.
A power conditioner or regenerator will transform the sound you have and give you what you looking for. It will remove the etched over detailed top end and bring forward the mid and lower bass. The sound will be relaxed and natural.
You really don’t know what the The Prima Luna and digital source are capable of until you give them clean power and isolate them from each other.
A big difference between mid priced and high end components is often the quality of the power supply so mid priced components benefit more from this type of upgrade, than high end systems.
Not all power conditioners are equally effective and some can be detrimental. Having tried several I have found that Shunyata conditioners work very well and you could pick up a second hand Hydra 2 or 4 for a just a few hundred $
it will also transform your guitar amp!
good luck.