Oh, you've really stepped in it now.

On my PC, I 3.5mm out of the motherboard into a vintage Pioneer XS-828 receiver which pushed a pair of Alesis MK 1 Monitor One's.

I ran across a used FX-Audio DAC-X6 on marketplace. Retired the pioneer and picked up a used PJ Miaolai M6 'tube' amplifier. I bought a 5-pack of vintage RCA tubes for a whopping $10 on eBay. So went TOSLINK out of the motherboard to the DAC and then line level to the PJ Miaolai and push those same Alesis monitors. Was definitely a step up in sound quality. But what made the difference? Was there a deficency in the 40-year old receiver? Probably. But offloading the sound processing from the noisy PC was a huge improvement in itself. Even the vintage RCA tubes made a difference compared with the stock no-name tubes.

Then, still not really satisfied with how music sounded on my PC, I replaced the PJ miaolai with an Aiyima A07 + Suca Tube-T1 'tube' 'pre-amp'. Alone, I think the A07 is detailed but sterile. The Tube-T1 adds tone controls and really allows the 'depth' and 'breadth' of the music to come through. Adds 'warmth'.

In conclusion, I think the biggest thing you can do for a PC is a DAC. But I believe there's diminishing returns when it comes to cost when it comes to DAC. And keep in mind, that better headphones will 'show' the shortcomings more than 'cheaper' (for lack of a better term) headphones. After the DAC, it's really where you want to go and how much you want to spend. Powered monitors can be great for near field listening. Finding the right combo of speaker and amp is important, too. Like headphones, quality speakers and amps will show the shortcomings in the chain. But here on the internet, we get all caught up in percentages of percentages and specifications that probably don't hold a lot of weight in the real world where rooms are less than perfect.

Mine isn't pretty. Those Monitors are grey and utilitarian. None of the 3 boxes match and I have a redundant volume on the Suca. In fact, if I don't turn down the A07 when I power everything up or down (PC Audio is on a smart switch that turns on when I get home and shuts off at 11), there's a huge thump from the Tube T1.

But I'm happy with how things sound.

For now.