At what distance are balanced XLR cables needed?

IME, more than 15ft.

Kijanki -- I agree 100% with your post just above.

I would additionally mention the fact that balanced interfaces will be much less susceptible to ground loop issues than unbalanced interfaces. That susceptibility can be length-dependent, because it is sensitive to the resistance of the inter-chassis connection path. But the length-dependency will be system-dependent and unpredictable.

Best regards,
-- Al

Anything over 3 meters, but I would still keep the interconnects as short as possible

Mariv26: Anything over 3 meters, but I would still keep the interconnects as short as possible

I don't think you can make such a general recommendation. It really depends on the EMI environment. OTOH, if you believe that there are no potential disadvantages, only potential advantages, to balanced interconnects, you might want to use them regardless of length.

Kal

Kal, Absolutely. Why not to use balanced if environment is known to be noisy. My Rowland 102, a class D amp, has only balanced input connector - a mature decision on a side of Jeff Rowland. Balanced has also two practical advantages - it won't disconnect (latch) and prevents touching input (exposed side always female with recessed sockets). The only disadvantage I know of is a little higher price.