I am not familiar with the Armando; however, CAT7 cable is not intended for analog audio use even when it’s shielded. Frequently, a hum issue will be the result of either a coupling problem due to proximity of AC mains lines when run with the CAT7 in the walls or a ground differential issue or loop between where your turntable is plugged in than your system across the room.  Since the RIAA amplifier in the 7000 is not a balanced output there is no common mode rejection along the signal run. I would approach determining which type of hum you have by running a CAT7 cable across the room in lieu of you in wall set up. If the hum goes away you have in-wall coupling which may be mitigated by using isolation line transformers to convert your single ended connection to balanced on bot sides.  If the hum is sill there you then have an AC mains grounding issue, and you need to disconnect the grounded shield from the Almando end. You also might try reversing the mains plug on one side if its a 2-prong one.