Suggestion on XLR Cables

I've seen some Synergistic CTS (used) at about $1000.  Cable's got great reviews and I like their power conditioner.  I'm not high on another AC connection (for the active piece of the cable).  Audience SE (1m) available around $1000, SX about $1250.

I've heard some of these "giant killer" cables.  I'm not saying they don't punch above their weight because a # of them do but they are bettered by some others I mentioned.  Now are those worth the price differential, that's up to each person to decide.  BTW, I've got Duelund's in the system now. Don't know what the fuss is all about. None of their wire (made into cables) sounded good in my system. Not as XLRs, not for speaker cable. Maybe it's a synergy thing.  Always too bright for my ears.

So I bought a pair of KLEE Acoustics TruBalance Interconnect XLRs that arrived today to use with my NAT Audio Magnetic Preamp. I got that preamp about a month ago to replace a PS Audio BHK. I like the NAT better but thought I could use a cable upgrade. I’m running Duelund wire XLRs from my PS Audio DSD to the NAT and Audioquest Columbia XLRs from the NAT to my PS Audio BHK amp. Not that it matters for my question but my speakers are Wilson Duettes.

Anyway, I swapped the Duelunds for the KLEE cables and switched on my system. Hmmm. More like hummmmm and volume ~6db lower than with the Duelunds. Put the Duelunds back in, everything’s back to normal. I called the dealer who was really cool about it. Suggested I put the Duelunds back and swap the Klee for the Audioquest(running NAT to Amp). I was feeling lazy but plugged the Klees into OUT2 of the NAT, disconnected the Audioquest from the amp and plugged in the Klee there. Still low volume issue and hum. Put back the Audioquest (NAT to amp). Low volume still exists, same for hum. Weird I think. Until I remember Klee cables are still plugged into OUT2 of the NAT (though not plugged into anything on other end). Unplug the Klees from OUT2 of the NAT. Volume back to normal, hum gone. Plug the Klees back into OUT2 (unconnected at amp end). Hum and lower volume issue return.

Either a) something is seriously wrong with the KLEE cables (left & right) which I doubt (as does dealer) or something about the KLEE really upsets the NAT. Almost like the NAT is shorting out though obviously not fully. Dealer has been a prince and offered to take the KLEES back but I’m curious if anyone that has a lot more knowledge in this area than I do has any idea what’s going on.

Thanks in advance.