When it comes to phono hum, you just have to experiment. Especially with a SUT in the mix. I have a couple of the Pangea ground cables hanging around because they're good quality, and it's good to experiment with a free ground cable.
Turn your system on, mute off, put volume to a low-ish reasonable level so you can *just* hear the problem hum (lower than usual listening level - you don't want to cause any nasty high-level pops) and firmly but loosely (just contact-based) connect the ground cable to various contact points to see if you can find the magic quiet configuration.
With my SOTA table I need to use the DIN phono cables's integrated ground (to arm) PLUS a separate ground cable tied to table chassis/bearing - both then tied to SUT on other end. When I had an RCA / RCA phono cable with separate integrated ground (spades on both ends - probably just like your cable), coming out of SUT, it was always a mixed bag:
- Sometimes tying both spades (SUT and phono input) was quietest
- Sometimes tying neither spade worked
- Sometimes typing ONE end (usually SUT side) worked best. This is generally a "best bet" and replicates the typical shielded RCA cable having its shield tied to ground on SOURCE end only (arrows point AWAY from source end). The SUT chassis becomes the main ground reference in this scheme

