Needing to replace thirty year old speakers.

1) Don't dismiss used out of hand, you can get a great deal on used and people who buy expensive speakers generally take care of them.  I got killer deal on used speakers (think 80% off list) especially at dealers who don't sell a brand but take them on trade-in for good customer

2) Every speaker is enhanced with a sub, even a small sub.  But it sounds like this is a wife-acceptance thing. If you primarily listen to  classical music or even jazz from the 50's & 60's, they're probably less important.

Realistically, your Cronus Magnum Probably only puts out 10, 15, 20 watts per channel at best over the range of human hearing and still maintain a maximum distortion level below 1% to 3%. Don't believe the 100 watts per channel hype. That's just the way it is with tube amps. It still will easily drive many of the moderately efficient speakers out there.

As @celtic66 suggested the ATC SCM40, a bit out of your price range though but deals can be had if you can find a retailer that carries them. They are wonderfully made mostly by hand except for the enclosures which are outsourced from a local vendor. The drivers have enormous magnet structures with underslung voice coils and all their parts are meticulously fabricated and assemble by hand. 

Since it's a sealed enclosure the bass roll off is relatively slow and will still have prodigious output below it's -6dB 48Hz specification. In addition, it will present a fairly benign load to your tube amp because that tends to be the nature of acoustic suspension speakers. Something to consider.

As others have mentioned, ProAcs, Revels, Dynaudios, which tend to be on the brighter side and Klipsch's though incredibly efficient are not necessary unless you're into headbanging or something. I think the Wharfedales, MoFi, and Sonus Faber are good recommendations and worth seeking out. You may even find a speaker among their lines well below your maximum of $5000.

@mbruflodt25 

Fischer & Fischer SN170's. A tad more than $5k at $7700 but worth looking in to and saving up for. The slate makes it the best choice. .

The SN 70's are really good too. $5500. 

@mbruflodt25 “Me to delete the subs my wife would be happy” 😀

Some people like being a “sub” but that’s for a different forum. 🫡

Most people like a sub (woofer)

Tell the wife, well set up subs are heard but not seen. They disappear in the room. Problem solved.

It depends on how important it is for you 

I saw the title of your post and automatically thought 'I wonder it they're Cantons'? LOL I was right because I have a pair of 40 year Canton Karat 200s that still play quite well. The spring clip connector on one of them has started to get a little loose but it still plays. Good bass too. I have them in my vintage system along with a Denon PMA 757 amp and B&O turntable. Mid-80s lushness.