If you've ever heard a 'flutter echo' with the clap hands test, you'll know what a horrible thing it is. Mine was bad. I suspected it wasn't doing the sound any favours.
I covered 2 walls with the thickest cork tiles I could find. And the ceiling with a raised-squares pattern, fire hazard, similar to this:
https://www.amazon.co.uk/Polystyrene-Ceiling-Tiles-Welle-White/dp/B00D07650O/ref=pd_lpo_sbs_60_img_0/261-0104565-6448621?_encoding=UTF8&psc=1&refRID=KEG31VPCNHXRXJ6Y5SY2
The result was an instant focusing of all sound. A genuine upgrade, second only to an ear syringe.
It's laughable to consider cable changes before addressing room acoustics (and some would say even after!)