Frankly, I dont think you need worry too much about either placement. That said, between the two speakers is neither the quietest nor the best looking place for a piece of gear. OTOH, the long TT lead IC will slightly affect the loading parametres, but the Gryphon phono does offer some adjustments, so I wouldn't worry about that either.
In my case I much preferred my TT comfortably placed to the right of the right speaker, against the side wall. Mind you, I had a standalone phono, so the TT-phono connection was shorter than yours.
I also like looking at the open space between the two speakers -- but that's just me.
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