Need 25 foot interconnects

I would recommend a good cable company. My minimum is DHLabs. I have tried Blue Jeans and Belkin and found them to be equivalent to the quality that you get in boxes with inexpensive and mid-fi products.

Spoke too soon about no hum.  It got really quiet in the house tonight and had a good listening session and left the earlier comment where I said "No hum. No noise."  When I stopped playing music and stood up, I heard a slight hum.  I got closer to the speakers and they just have a monotone hum coming out of them.  Going to need to troubleshoot the hum this week and figure out the cause.  Lots of things going on that are different -- also switched from low level subwoofer connection (interconnect) to high level coming off the speaker binding posts, so not sure if it's the 15' interconnect or the high level subwoofer connect that is causing the hum.  Maybe the hum is making the soundstage better.  ;-)

+1 @ghdprentice . In my den I have a pair of Kef R11 being driven by PS Audio M700 monoblocks.  I took a pair of Audio Quest Rocket 44 cables cut them in half and am biwireing. The bass has improved so much I have turned off the sub. Big improvement over 8ft runs. I would also use RCA and an adapter to another pair of equivalent RCA of 10ft. Try to keep them clear of other cables. If it sounds good then spend the coin for a better pair.

As others have mentioned, the starquad configuration is best for a noisy environment. Canare L-4E6S is the very best because the shielding is the best: heavy, braided, pig to work with. Mogami is almost as good, but the shielding is twisted, so not quite as effective, but a whole lot easier to work with.

Add some decent connectors like ETI or KLE and you can't do much better. Switchcraft is pretty good too, for that matter, at bargain prices.

Belden? what kind of cheap monoblocks do you have to use that crappy cable?

Nice gear shaming @urbie -  however solid gold cable also seem to obey the laws of physics.

Spoke too soon about no hum.  It got really quiet in the house tonight and had a good listening session and left the earlier comment where I said "No hum. No noise."  When I stopped playing music and stood up, I heard a slight hum.  I got closer to the speakers and they just have a monotone hum coming out of them.  Going to need to troubleshoot the hum this week and figure out the cause.  Lots of things going on that are different -- also switched from low level subwoofer connection (interconnect) to high level coming off the speaker binding posts, so not sure if it's the 15' interconnect or the high level subwoofer connect that is causing the hum.  Maybe the hum is making the soundstage better.  ;-)

This is great.
Great to find this out now.

Is it easy to run an extension cord to the mono block?
That “test” could allow us to determine if the monos are on a different circuit.
Or you can flip breakers to work it out.

Your trouble shooting plan sounds good.