Without more info on the components in your system, I can only guess. The problem seems to follow whatever input you use for a TT. I would start there. The first thing I would do is check the settings on your phono preamp. Too much gain will cause all kinds of problems. Its very common to have a high output MC phono cart and use it with regular MC settings on your phono preamp. If you do have a high output MC cart, you will probably need to use it on the MM setting, even though you don't have a MM cart.
Aside from that, something may be broken. A soldier connection that is starting to fail can make the noise you hear. I would start replacing components, one at a time until you isolate the one that is causing the problem. Start with cables first, just because they are the easiest and go from there. You should be able to figure it out it this way.
Aside from that, something may be broken. A soldier connection that is starting to fail can make the noise you hear. I would start replacing components, one at a time until you isolate the one that is causing the problem. Start with cables first, just because they are the easiest and go from there. You should be able to figure it out it this way.