i think the fw j2 will allow you to hear differences in sound among dacs (ares vs node etc) than the cary, which will tend to homogenize the delta and promote it’s own sonic nature
regarding dac upgrades, over the longer term, i think you will hear a bigger step in sonic improvement if you went to a denafrips pontus or schiit gungnir mb or yggrasil (or a chord qutest or gustard r26)