First impression is usually correct. If you don't notice immediate difference when you changed something, there probably was little or no change. If there is a slight change in nuance that can be noticed only with extended listening, then you'll need to decide whether the change is worth the cost of the new gear.
I have different philosophy with swapping cables than swapping components. Swapping cables is more like a tweak, or something fun you can do on the side. I would first start swapping cables with friends and establish a baseline as for what kind and how much change can be expected. Going to different brands is usually more noticeable even at the same price range. Change in the speaker cables is usually more noticeable than change in interconnects. If you are rather skeptical or don't find the whole process fun, I would recommend saving money and upgrade other components instead.
I have different philosophy with swapping cables than swapping components. Swapping cables is more like a tweak, or something fun you can do on the side. I would first start swapping cables with friends and establish a baseline as for what kind and how much change can be expected. Going to different brands is usually more noticeable even at the same price range. Change in the speaker cables is usually more noticeable than change in interconnects. If you are rather skeptical or don't find the whole process fun, I would recommend saving money and upgrade other components instead.