Yes - a good point about the USB. If you were to plug it into a different USB port, for any reason at all, the computer would see it as a 'new device', and would search for or ask for the driver to be installed again. So best to consistently use the same port.
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I too also turn the computer on first, then the Audio/MIDI interfaces, then start Sonar after everything is on and settled down after a minute or so, then finally my speakers.
The reason is that with my Audio Interface, which is a Presonus StudioLive 16.4.2 mixer, that there are a few visual spikes that show up & peak on the mixer meters during Windows start up, and are even quite loud if I happen to have the speakers on first.