Balanced usually
1/4" TRS connectors are usually balanced connections (hot, cold, ground - for shielding) except for some special applications (i.e. some mixers) where a signal is sent and recieved through the same connector.
Typically, for balanced connections, the ground is used to transmit the hot 180 degrees out of phase. It's been my experience that unless both pieces of equipment connected support balanced connections and the cable has to be reletively long (10 meters or more) you won't gain much benefit from using balanced connections.
Also, the number of conductors has little to do with the determination of balanced vs. unbalanced. Higher quality cable transmit the hot and cold in one or more twisted pairs of conductors becuase of two reasons. First, twisted pairs are more resistant to noise interference. Second, a larger number of smaller insulated conductors yields a much better frequency response than fewer larger conductors. This is because the smaller insulated conductors combat a phenomenon called skin-effect.
