I don't own both sets anymore, but "upgraded" to U853 cards, with maybe a month inbetween the use of the old style and the new, and noticed no difference in output or noise, or a vast improvement for that matter. But they performed just as well as my old caps. So I'm assuming you still have your old pair of caps and they perform well? It sounds like there may be something wrong with the caps, if there is no loose connection, or corrosion, dirt ect. on the inside tabs of the cap. Might be worth talking to Chris @ Soundpro's and having him take a look at them. They are very reasonable people.