Odd that, I'm using it via the Sansui directly and via the Spitfire and both are fine.
Interesting what you mention about "not entirely black", which I'd disagree with (not for the sake of it I should add). I tried out The Division Bell album which has rather a lot of quiet passages, also several of Brian Eno's "Ambient" series from the late 70s. I'm not sure how much "black" you'd want to be honest as the "sonic background" was about as quiet as you could reasonably ask for!
The "cheapish" CD player bit still puzzles me. Soundstage is good. It all depends on your amp and speakers as well - obviously enough - but I find, the more I listen to it, your position surprising. It's patently beyond "cheap" sounding, patently. It might look like a cheapo player, but performance is way over and above what you're reporting.
Bass depth is good, there's a nice midrange, the treble's a bit keen but not sharp or ear piercing - it sits to the fore, but there's enough going on elsewhere in playback to counteract what it's doing. Put it with bright electronics across the board and it'll lose friends. Partner it well and it's a winner.
I'd dump the cable if I was you...