macbook pro
so I bought a USB-C hub for my MacBook Pro 2017,
specifically, this one:
https://www.aukey.com/products/usb-c-to-4-port-usb-3-0-hub-with-hdmi-port-usb-c-charing-port-cb-c58
it has a power delivery USB-C port, and I'm wondering if it safe for my Macbook to always use that port when I have the hub plugged in (so I can use the other USB-C port on the mac for other purposes) or it is better to plug power directly into the Macbook? any technical differences?
I do not think it is a power problem.
Check in GarageBand if your device is showing up.
If not: I would start with getting the latest software for your MIDI device
Generally speaking, using a charger with a lower watage rating than the charger that came with the device will just mean that the device will take a longer time to charge. As long as the charger delivers the correct voltage (which is set by the USB specifications) it will not damage the device. Thus, if you trust that the charger properly follows the specifications laid out by the USB industry group, it should not pose a danger, but could take longer than a "proper" charger.
Using a charger with a higher watage rating should also work, but has the potential danger of allowing the device to draw more power than is safe for the device. In this case you would need to trust that the device maker has followed good design process and limits the power that it draws rather than just taking the maximum that the charger can push out.
I trust Apple not to allow their devices to draw more power than they can handle, and thus often hook up low power MacBookAir devices to high power MacBookPro chargers.
Best Answer
This should be perfectly fine, as it's exactly what it's designed to do. The port in question is a USB-C Power Delivery port and the 2017 MBP supports USB-C PD.
Note this hub is not the charger - it is merely providing the means for your 2017 MBP charger to be used to charge your MBP via the hub. As you're still using the Apple charger that came with your MBP, the actual power being delivered directly to your Mac should be the same, so in that sense there should be no technical differences.