We asked for a 2 pair cable, 
why do you suggest a Star Quad?

What is a 2 pair cable?

That's easy to answer. A 2 pair cable is a cable with 4 insulated cores, arranged in 2 individual pairs
Two different signals can pass through the same cable and each pair can carry one of them

How a 2 pair cable is different from a 4 core cable?

A 4 core cable has 4 cores twisted all together in one step, with common lay length
A 2 pair cable has also 4 cores, but twisting occurs in 2 steps. Step one: core 1 and 2 are twisted together to form a pair.  Same for core 3 and 4. Step two: the two pairs are twisted together

Why do we need 2 pairs individually twisted?

We do all this in order to prevent crosstalk. Crosstalk is electromagnetic interference from one pair to another. For applications where  crosstalk is not a concern, 4 core works just fine. If we want to avoid crosstalk then we have to choose 2 pairs, individually twisted. 

What is a Star Quad cable?

Now, this is getting interesting . Star Quad is a 4 core cable design where we choose our pairs from cores not adjacent, but opposite to each other.  By doing this we eliminate crosstalk, achieving the same good crosstalk values like individually twisted pairs.

So any 4 core cable is a Star Quad?

Not necessarily. There must be two conditions:
1) The manufacturer should make sure that the symmetry is maintained for the whole length of the cable (at Accordia we do). If occasionally, during stranding process, the relative position of the cores changes, star quad design is negated
2)The installer should use the opposite cores as a pair for connections
If adjacent cores are used, star quad design is negated

Ok, so a proper Star Quad, properly installed is the same as a 2 pair. Still why shouldn't I choose 2 pair in the first place?

Because Star Quad comes with additional benefits. One step twisting makes better use of the available cable space and the result is a more compact, mechanically robust and durable cable, with smaller outside diameter (especially when it is combined with a short lay length, as we do it at Accordia). 
Therefore cable withstands much better all forces during installation and keeps its electrical characteristics unaltered.

Note: this article is about a star quad cable used to transfer 2 different signals (two circuits). Please do not confuse with using a star quad cable for 1 signal (one circuit), e.g. in microphones.