Listened to those takes again with my 18-year-old son tonight.
I don't hear the static at the beginning of those takes, only in the last two takes with the highest levels. Keep in mind I'm mid-50's with tinnitus and fair hearing loss.
My kid says he can hear the static, but that it was really only noticeable when I cranked the treble to max. Maybe I'm blessed to either not hear it or just able tune it out from being used to listening to high-generation Grateful Dead tapes from the old days.
I'm kinda curious about what your expectation is for "sound quality" and the volume not being what it should be. From my perspective listening tonight the 2nd and 4th sections of that clip have about the right volume. 3rd section too low, 5th and 6th sections too hot. First section is just an RCH hotter than what I aim for when tracking vox, but I wouldn't discard a vocal clip that peaked at -8 or -10dBSF simply over level if it captured the performance I was after.
What dBFS level are you looking for when you track? Peaking at -12 to -18dBFS is the neighborhood you want to be in. Get too much hotter than that and you can run into headroom issues later. Much lower and you are going to have signal-to-noise issues.
I still think at least some of what you are hearing as static is actually sibilance and maybe a tiny tiny tiny dash of flutter echo--- not enough to sound phasey but enough come across as an artifact.
My son and I both agree that the sound "quality" all else aside seems appropriate for a raw vocal take with the setup you describe.
Arcaxis may have hit the nail right on the head with the stuff about a powered USB hub or outboard phantom power.