This has me scratching my head. I tend to be a do it yourselfer until I come across osmething I can't figure out where to start. This is one such item. I have a pipe coming out of the wall to a 90 degree shutoff vavle then from there I have tubing to the toilet. In the toilet (Its a Kohler) is the toilet tank fill valve and the outlet to the refill tube. The problem is in the last 6 months the entire toliet refilling is noisy. The velocity of the water coming out of the refill tube is fine. Its a steady stream but not forcing itself out uncontrollably either. Now if I take the shutoff valve by the wall and slowly turn it to the almost off postion the water stops rushing through this assembly as quick and the noise subsides. The problem with this is you can't flush 2 times one after another you have to wait for it tro refill which takes a few minutes rather than the 45 seconds or so it takes when the valve is open all the way and noisy. The noise seems to come from the toilet itself and not from the wall or the tube going to the toilet. Is it safe to deduce its probably a defective toilet tank refill valve?