I certainly have a world of respect for Craig... so I'm not saying this to be argumentative.
Many USB2 audio/MIDI interfaces have compatibility issues with 3rd-party USB3 controllers.
We've seen this many times. That's not to say some combinations won't/can't work... you're just increasing the odds of issues.
Very similar to using a non-TI chipset Firewire controller.
A quality unit (RME, MOTU, etc) will have clean audio when connected to motherboard USB ports.
Poorly grounded/shielded audio interfaces (often less expensive units) are more prone to picking up noise.
Cheaper bus-powered units are typically the worst case scenario.
I've experienced issues with a poor quality USB cable introducing noise (MOTIF ES7 connected to motherboard USB).
Swapped out the cable... and the noise was gone.
I mentioned this in another post...
My current motherboard is a Z170x unit that specifically has a pair of USB ports for connecting audio interfaces.
These dedicated ports are advertised as offering, "Clean, low noise power."
I've measure the average noise-floor of the Fireface UFX when connected to these ports... vs. the standard USB ports.
There is zero difference in the average noise-floor. (Note that the UFX was not bus-powered)
If possible, I'd avoid bus-powered audio interfaces.
Especially if you're using condenser mics (which require phantom power).
Higher-quality units like the RME Babyface will be fine.
(Note that the Babyface includes a USB cable with 2 USB connections - to insure it's getting enough power).
With lesser units, it's somewhat setting yourself up for failure (noise and lower fidelity, weak phantom power).
FWIW, PCIe controllers are connected to the PCIe bus... and plenty of electronic circuity (powered via the PC's power-supply).
A poorly designed audio interface will still be subject to picking up noise.
ie: Years back, I had a M-Audio FW1814 (Firewire audio interface).
Even when connected to a quality PCIe TI chipset Firewire controller, it was prone to picking up computer related noises.
post edited by Jim Roseberry - 2016/04/10 17:41:22