USB can't offer as low latency as a piece of well-designed hardware plugged directly into your PCI bus, at least in my own limited experience. This comes into play when doing music keyboard recording.
eg. I found it difficult to find a USB MIDI adapter that didn't introduce unacceptable latency (when trying to record new tracks synced in real time to existing ones). Edirol was recommended to me but even after tweaking settings for hours it fell short. I wound up buying a second-hand Creative X-Fi Elite Pro PCIe card and love it.
I don't think it's a USB protocol problem but rather a driver/manufacturer problem.
This may be true but I've never had latency issues with USB soundcards. Right now I have a Line6 Helix Floor unit that I use to play guitar with. I can route the audio through the Helix effects, into Logic and back to Helix for more post-processing and have no latency problems.
I have had other brands and models and none introduced perceivable latency.
I don't use MIDI but I doubt it requires less latency than live guitar playing.
I had a PCIe soundcard a few years ago that made it almost impossible to get rid of ground hum though.
Last time I did audio, installing ASIO4ALL was essential.
Or get an external MIDI clock like the E-RM Multiclock and never bother about MIDI latency issues. Audio is completely fine, 30-50μs of latency won't ever be perceptible to humans, the latency of MIDI will.
In particular, the first readily available set of benchmark results I was able to find[1] suggest the difference in audio (not MIDI) latency between the lowest-latency PCIe cards and the listed USB devices (RME Fireface UFX+ USB3 and RME Babyface Pro [USB2]) is under a millisecond.
While I couldn't find similar results for MIDI I/O, it seems unlikely that either of these USB devices' MIDI interfaces would introduce an order of magnitude more latency than their audio counterparts.
[1] https://gearspace.com/board/showpost.php?p=15796206&postcoun...
https://www.bleepingcomputer.com/news/security/heres-a-list-...
Then there's Korg's Oasys PCI, which was so powerful that for a long time people kept using Windows 98 after Korg stopped making drivers: https://www.soundonsound.com/reviews/korg-oasys-pci
So USB is pretty good, and for most sound card, USB2 is enough. Otherwise you can go Thunderbolt, which offer on par experience with PCIe.
What a consumer sound card offer now a day is better dac compare to the one of your motherboard or better output for headset.
Ok, I just checked, and a 192kHz 24-bit WAV file is only 0.56 MB per sec. Nice.
...in part because there's no way to do that, and if you do it by using the headphone jack, in addition to low quality you're also going to get all system sounds
I don't think most people know what spidf toslink or RCA even are.
Modern CPUs can ether do or emulate this, probably using less power than a sound card.
Very, very, few people have their PCs connected to an AV receiver or multichannel speakers, but positional audio is still widely supported in Windows applications using Xaudio2.
The reasons sound cards went away is the use cases went away:
1. People who want high quality recording shifted to firewire and later high-speed USB external audio interfaces. No matter how hard you try an external metal box with multiple inputs and outputs will always be better than a PCI/PCIe card inside a PC for recording. Rare use case in the recording world for sound cards.
2. Gamers who want 3d/positional audio either use headphones, find the 5.1 integrated outputs to be adequate, or like me, run a digital audio cable to a surround sound receiver. Rare use case in the gaming world for sound cards.
Dolby Atmos is awesome for positional audio in games but there are multiple less expensive and more accessible methods for surround audio nowadays. Decent positional audio can be experienced using a laptop and headphones-- no sound card required.
https://www.pcgamingwiki.com/wiki/Glossary:Surround_sound
Back in the sound card days you had to squint on the back of the box and ask "is this creative 3d? aureal?" nowadays you just plug in 5.1 to your PC's onboard audio, tell windows you have 5.1, and it works (mostly).