Good choice and lucky find. I live in Japan and I've had a pair of NS-1000X's for many years, and like them so much I finally got a second pair. I've A/B compared them to many, many high-end speakers and in many systems at the shops over the years, and I am convinced they are among the best all around speakers ever made, and certainly so in their price range. Few speakers can compete with them across all musical genres, and they play all the positives and expose any flaw in your system clearly.
The NS-1000X has the same wonderful beryllium dome midrange and tweeter as the NS-1000M, but a better woofer, made of carbon fiber, and a heavier cabinet. The sound quality is similar to yours, but with improved bass.
The NS-1000M is very common here in Japan, and they go for about US$500 in ok condition to about US$800 in minty-new condition. Unless yours is a flawlessly new-looking collector's item, which from the "dirt on the speakers" it sounds not to be, a modification of the terminal would not lower the price here in Japan. I've seen several units with such modification in the same price range as for unmodified units here.
The NS-1000X's have a screw-type terminal with holes too small to run thick cable through. On mine I just painstakingly stuff as much thick Monster cable into the holes as I can. I use heavy Monster cable that I've had since the '80's, because that was the going thing at the time the speakers were made and used by many recording studios here at the time. The sound result is excellent.
As for stands, there were wooden stands made for them originally, and not difficult to find through Japanese shops and auctions on the net. Their virtue is an angled board at the bottom that projects the bass outward.
I have two different systems in different rooms, and different approaches to stands. In one room the floor is soft tatami mats, and so I have first a wood sheet, then a marble slab, both about half an inch thick, and then brass cones that are fitted on stone cylinders about 2 inches thick. The cones are thus sandwiched between marble. They are not expensive cones, about US$8 each or so. In this room I usually sit on the floor or listen in bed, and the height is fine, with the tweeters at about ear level.
In the other room I usually sit at a computer desk with the Yammies behind me. These are up on cement building blocks, and isolated with stone tiles and then the same kind of cones on marble cylinders.
I tried loads of isolators and stand systems over the years, and these work well for me. The cones sandwiched between stone really sharpen-up the bass especially, and make everything even more clear.
Welcome to the Yammie sound world. It will be difficult for you to change from here.
What I do is have fun pairing the Yammies with various bookshelves, rather than trying to replace them with anything. To do this I use wonderful old Luxman amps that run 4 speakers as A+B.
In the tatami room I have them paired with B&W805s. This combination is great. The 805s absolutely pale in comparison to the Yammies, but their high-end tweeters are sweet and somehow they synergize when all 4 speakers are on.
In the other room I currently have Quad 12L's, which are warm speakers and not very neutral, but somehow make nice contrast with the Yammies on a lot of music. I find this combination a little lacking, and still seek a better match. Today I'll compare them to some Sonus Faber Concerto Homes, but I feel those are too far from the clear Yammy sound I like. Perhaps the best bookshelf match for me would be Adam A7s.
But I ramble....
