At what distance are balanced XLR cables needed?

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.

IOW if you can hear differences in the cable between the line section and the power amp, then the cable is not being controlled.

Hmmmm, now there's a pretty serious generalization. I have heard significant differences between IC's in the critical line-stage to amp link with Audio Research, CAT, BAT, Aesthetix, Aria/Counterpoint, to name a few products. Are you claiming that the designers of these products are not competent to "control" the cable?

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

Agreed, as my own experience voids such a generalization.