Are Expensive Balanced Interconnects Necessary?

I run XLR between preamp and monoblocks. After using for some time only RCA between DAC and Preamp I decided to check XLRs. With equally expensive RCA and XLRs the difference was subtsantial. Initially it was hard for me to say which one I like more as they offered tottally different musicality. And on top the aforementioned gain with the XLR further blurred the picture. I do not understand a lot about harmonics, but noticed that although the treble was somehow more fluid with the RCA it was also more fatiguing at higher levels. Probably due to different harmonics. XLR delivered more focused sound and definetly was more quiet. I lived for some time with both switching back and forth, but a bit surprisingly for me I left with no regret the XLRs in my system.

@cleeds Thanks for providing an example supporting ‘it depends’. 

I specifically purchased a Denafrips stack (Pontus II DAC, Hades Pre-Amp, and Thallo Amp), in part because they are true balanced devices throughout......in fact the Thallo amplifier only accepts XLR inputs.

I am running Morrow Audio MA4 XLR interconnects (right now have a deal for 45% off with code SAVE45)......that comes out to about $181 for a 1 meter pair. For the price certainly worth a look

That's not at all how a differentially balanced circuit works. A differentially balanced circuit uses both an inverting and non-inverting signal at its input, then amplifies the voltage difference between the two signals to produce the output.

Depending on the design of the balanced circuit, there can be substantial benefits to using it in balanced mode, rather than SE. For example, with ARC balanced preamps, you'll get 6 dB more level using it in balanced mode. That means 6 dB improved s/n.

Maybe when noise is zero… @cleeds ?

But the idea of CMRR is usually more than 6dB.
Let’s look at each side:

• (+) S + N
• (-) -S + N

(+) - (-) = S + N - (-S +N) == 2S 

Balanced cables quieter and more dynamic.