Yes, in answer to the original question. Anyone who debates they don't make a difference maybe hasn't tried a PC that can make a difference. The change in sound can be obvious. It is more obvious for some components than for others.
I had switched from stock PCs to Nordost Valhalla PCs. Valhallas can make bass tighter and highs more detailed. For some equipment this was good, for others not so good. For example, for kicks I tried a Valhalla PC on my old Denon 2600 DVD player, and the bass became almost non-existent (not good). But it was interesting to hear such a difference. WMMV.
I had switched from stock PCs to Nordost Valhalla PCs. Valhallas can make bass tighter and highs more detailed. For some equipment this was good, for others not so good. For example, for kicks I tried a Valhalla PC on my old Denon 2600 DVD player, and the bass became almost non-existent (not good). But it was interesting to hear such a difference. WMMV.