Question. Has anyone noted any sound quality improvement with the Pi 4s as far as streaming over the USB ports? I thought I’d read that they were more isolated than the shared bus design on the 3s.
Thanks. RoPieee is amazing software. Donate if you can-this is a worthy cause!
Yes, but that wouldn’t affect SQ strictly speaking, it would affect their ability to keep up with streaming. Which with the Pi 3 could cause pops and skips, though not always, so if you consider that SQ…
I get the clicks and skips and sometimes it will just randomly pause. I should compare WiFi vs wired too I guess but I’m generally distrustful of 2.4 GHz band WiFi vs 5.
Chromecast Audio doesn’t display that kind f behavior. I suppose I COULD just stick with what works, but what’s the fun in that?
The controllers for the USB and Ethernet are separated on the Pi 4. May avoid some clicks and skips you can (sometimes) get with the Pi 3. But it’s also unnecessarily faster and hotter. So those are the trade-offs.
I thought the heat issue (caused by the USB subsystem, not the CPU) was being addressed by new bootloader software? See here:
So, no more fan?
No idea, I don’t have an RPi4 - still happily using the older generation.
I can’t compare with a Pi3 as my first Raspberry Pi is the 4, but I am listening via the USB and it sounds fantastic, very detailed into my Mojo DAC (and for £70 all in the Pi4 blows away the Auralic Mini at £449 USB output for sure so I’m a happy bunny and the Mini is going on eBay!). The USB circuit layout has changed and I have seen several write-ups saying that in theory this should improve SQ. In my experience USB handling does impact SQ just as various USB cables sound (to my ears after prolonged testing) different - but I am thinking this really depends up on your DAC and its receiving of the USB data as much as anything - which is probably why others disagree and say both make no difference at all. 
This is a bit OT but 2.4GHz could well be more stable than 5GHz depending on the circumstances, since it is more penetrative of intervening walls etc.
Max bandwidth is around 450Mbps for 2.4GHz wifi so in theory it should be fine for most audio streaming tasks provided your signal is strong.
Wifi wont do for the Roon Core though, that should always be wired for reliable performance.
My core is a NUC in the basement attached direct to my networking cabinet via an Ethernet gigahertz switch.
2.4 GHz around here is dicey with too many networks nearby plus neighbors with crappy microwaves that cause signal drops which is why I have Airport routers on each level of the house and generally use the 5GHz band. May be overkill but generally things work pretty well.