Hiss in my Recordings

Hello all! This is my first post on this illustrious community. I've searched the forums, but couldn't find an answer to my specific question.

I am using a Behringer Xenyx x1204USB mixer, a Shure SM58S microphone. I use Audacity to record and edit.

All my recordings have a barely audible, very high-pitched hiss in the vocals. This hiss seems to get louder the higher up I turn the compressor built into the mixer. I currently have the compressor at the 9 o'clock position for the channel I have my mic connected to.

Currently I use the Noise Reduction tool in Audacity to remove much of the hiss, but it doesn't get rid of all of it. I'd love to remove the hiss at the source, so it isn't in the recording at all. I've read about using a ground loop isolator, but I'm not sure if this would solve my problem as I've seen people say it removes a hum (I have no hum) from the sound, but I've seen no mention of removing a hiss.

I've tried moving my mixer as far from my computer as possible, and I've tried uncoiling the mic cable and moving it various ways. None of this has had any effect.

Can anyone give me any ideas of how to remove the hiss? Would a ground loop isolator help? Ideally I'd like no hiss to be there in the recording (I can hear the hiss over my headphones while recording), but if the only solution is using Audacity's Noise Reduction, maybe someone can advise me as to a better way to use that tool.

Thank you in advance to any help anyone can give me. Also, feel free to let me know if you need more information about my hardware.

Please post a short file (with pauses) that clearly demonstrates the problem. The hiss could be coming from a ground loop, but it's not likely.

Try also recording a session without the mike plugged in and the gains on the channel turned up. You may be hearing the noise on the mixer channel itself.

Would like to also hear a recording