Real experience - Balanced or Unbalanced between Luxman Pre & Power Amps

Other than preferring to use balanced cables I hesitate to offer advice beyond that. Your Luxman pair is voiced a little differently from mine and your speakers aren't voiced the same (mine are Tidal Piano Ceras.) From what I've heard of ATC speakers, they should be a very nice complement to the Luxman sound. I use Cardas Golden Presence speaker cables and they sound so nice with the Luxman (and my other amps) I've never had much interest in replacing them. I imagine Cardas interconnects would be a good place to start. I have to give TMR audio in Colorado a nod as a good place to shop for cables, especially used ones. They let you send back anything that isn't working for you and all you're out is shipping. 

I'll bite.

Reiterating Ralph Karsten's (atmasphere) opinions, your equipment should follow AES standards for Balanced operation (that you are using Luxman equipment, I 'think' you should be in the clear, but having no wiring diagrams, I couldn't say for sure.

That being said,

I bought a set of Mogami XLR cables from Ralph, when I bought his amps and preamps (tubes). I followed my favorite dealers recommendation and tried some AQ XLR cables (non DBS). To my ears, it, too, didn't yield a significant difference.

I will say,

I have used AQ cables for my system after I heard the William Tell speaker cables. They were truly mindblowing in the sound difference from my GO-4's. So, I think that if I were to move up the line to a 'higher' cable, I might be able to hear a difference in XLR cables.

Is that worth the cost?

I love my system as it is, and am in no hurry to spend more. 

HTH 

Bob

Input impedance LINE : 45 kΩ/1 kHz
BAL LINE : 90 kΩ/1 kHz
LINE → BAL LINE : 27 kΩ/1 kHz
BAL LINE → LINE : 54 kΩ/1 kHz
Output impedance LINE : 90 Ω/1 kHz
BAL LINE : 180 Ω/1 kHz

But that is of no real concern. It's quite common for fully balanced audio gear to use another approach. You still gain the benefit of CMRR.

Thanks all and I appreciate all the input.  I'll find a local store that has some cardas options for me to test.