I love the Acutex 320STR III, and I have used it on my Dynavector DV505 and (believe it or not) on my Fidelity Research FR64S, where it really should not work because of the high compliance/high effective mass mismatch. I did use a lightweight (8 gram) headshell on the FR. The DV505 and 501 would have very low effective mass in the vertical plane and high effective mass in the horizontal plane. That is the deliberate intent of the design. There is no reason your Acutex should not work well on the DV501. I would suggest you look elsewhere to solve your problem, but buying a new tonearm is always an adventure, if that’s what you’re after.
Sorry, I did not see the above post where you say you would prefer not to replace the DV501. I agree. Can you say in more detail what you hear that you call "feedback"?
Sorry, I did not see the above post where you say you would prefer not to replace the DV501. I agree. Can you say in more detail what you hear that you call "feedback"?