It’s possible some of the sounds you hear with your ear right on top of the harp are not heard several feet away, especially when dealing with bass notes. Weird overtones might occur, phasing, etc. at specific locations away from your instrument. The bass sound wave is fairly long, and takes several feet to properly set up sonically. If you’re having problems with the sound of your harp, get someone else to play it and see if the problems you hear while playing the harp persist several feet from your harp. Locate the exact distance and angle these sound problems show up. If it occurs everywhere you listen, you have a true woof innate to the instrument, either due to construction or perhaps quality issues with strings. If it occurs at only specific locations, it might be more of an ambient sonic issue, which is still a real pain.