I bought one just for the hell of it but I've changed so much around in my system it's hard to tell if it made any difference.

Main system: 818v3, 861v6, HD621, Oppo 103D, DSP8000PP, DSP7200SE HC, DSP3200, SGR Sub
Family room: HD621, 861v6, DSP5200 L/C/R
Headphones: Schiit Mjolnir v1, Sennheiser HD800; (office) iFi iDSDPro, Focal Elegia