Which makes the biggest difference?

On my difficult to drive speakers the 4 amps I have had on them made a difference. It was not huge but on certain music the more powerful amps at 2 Ohms made a difference. I could also tell the sonic signature of the amps but that difference was not huge.

I have had a few DACs in the house, tube, warm SS, and neutral SS, and they made a smaller difference. The tube DAC softened things up while the SS amps were much closer in sound. When I added a Convolution filter for my very revealing headphones I could not tell the difference between the 2 SS DACs. The filter worked mostly on shaping the high frequencies. I also think DACs are of very high quality these days, with most sounding very close to each other.

The preamp I now use, a warm and detailed piece, made a huge difference over the very neutral preamp I way using before. Especially so in the bright headphones I use.

When I switched from Ethernet to Fibre Optical streaming I had the biggest jump in performance. It was not even close in my setup.

1) Streaming
2) Preamp
3) Amp
4) DAC

BTW - A preamp ALWAYS improved the sound in my setups. One of my DACs also does not have a volume control (a feature in my opinion and not a deficiency)

@artemus_5 Here is a link to how I got going with Fibre optical streaming. I ended up with 2 Sonore OpticalRendu’s. I bought the second 1 immediately after listening to the fist one. I have 2 DACs. I am also a big ROON user so ROON READY was a must for me.

https://www.sonore.us/systemoptique.html

I did not setup my streaming exactly as described above. I used the following network switch instead. Which has 2 Fibre slots.

https://store.ui.com/collections/routing-switching/products/unifi-switch-8-150w

A recent lesson I learned the hard way was not to put the ROON Server on a computer connected to the home network via a PowerLine network, put it on the regular Ethernet (in any room). With high res music I was getting drop outs which made my think my speaker drivers had gotten damaged. It was with George Harrison’s 50th ALL THINGS MUST PASS. On the song HEARR ME LORD my drivers would sound distorted during busy home internet traffic times during the passages when he is humming. It only happened on that song and was reproducible the times it happened. Luckily I figured out it was the streaming before I took more drastic measures with the drivers.