Please Help

Hey All. Pretty new to the recording scene but I love audacity! I have been playing around with recording some instruments ie. guitar, bass etc through mixing desk but theres a hiss/buzz in the background. I know how to get rid of that using the noise removal function. when i use it though, the buzz is gone but it sound like theres a chorusy/phasey effect on the instrument and also it sounds as if there major feedback! anyone know what wrong or can help?

Appreciate it

It’s usually best to minimise buzz/noise at source rather than relying on post-processing.
How exactly are you recording, with what equipment? Do you have a good level on the mixing desk? What sort of mixer? How is the mixer connected to the computer? The more information you supply the better.