RV, as I recall the interconnect you replaced was an older "networked" cable, which was explicitly stated by the manufacturer to have been designed to alter the signal. So in my opinion replacing it with a non-networked cable, as you did, can only be a step in the direction of greater accuracy. Which I would consider to be a good thing. And if that revealed a need to change something else in the system, such as the preamp tubes you indicated you changed with good results, that would be another step in the right direction.
Best regards,
-- Al