For a cable to be balanced, it must have atleast two cores which are shielded and twisted around each other. Keep in mind that having a balanced cable does not mean you have a balanced circuit. To have a balanced circuit, you must have balanced cable, balanced connectors (TRS or XLR) and balanced sockets. If any of these are missing from the circuit, it will automatically disable any balanced circuitry and form an unbalanced circuit.
This will not be a problem (as far as fidelity is concerned) if your cable run is 3m or less. At 3m, HF (high frequency) starts to degrade and gets worse and worse as the cable run gets longer. Unbalanced connections are prone to EFI and RFI though (interference).
So in your situation, you cannot have a balanced circuit because you dont have balanced sockets. Make sure your cable run is under 3m and you should be fine.
Also, run all your equipment off the same power outlet (provided this wont cause overload) as this will reduce hum which may enter your signal.