At what distance are balanced XLR cables needed?

Thanks Kal. When discussing the output current, I'm assuming you meant my HT's output. If my apartment is relatively noise free, any concerns with running about 20 feet unbalanced given the d2v's impedance?

Kal, 10 meter unbalanced and no problems? How did you manage that? Unbalanced runs tend to act like an antenna in my experience, I had to resort to long runs of balanced interconnect to mitigate the attenuation.

There are no guarantees. I have heard of people resorting to balanced cables for much shorter lengths because their situations involve lots of EMI. (Do you live near a radio/TV transmitter?) Recording/mastering studios have miles of cables all influencing each other.

So, my cables are no less antennas than anyone else's but, as far as I can tell, they are not picking up any signals inside my apartment. Literally, YMMV.

Kal

If Zone 2 is really 51 ohms you could use that output. 300 ohms is a bit high for solid state but it will probably be OK.

Bear in mind that you can spend an arm and a leg for unbalanced interconnects made with exotic wire. Balanced interconnects don't need exotic wire, and might cost you less.

Eldartford - you can spend arm and a leg for a balanced IC as well. They're also made of fancy materials - both metals and insulation. There is no reason why it should be different IMHO. Purity of metal still applies since impurity reside between crystals while insulation material directly affects capacitance and dielectric absorption.