Bookshelf/Small Speakers

You have 3 great brands from above to explore: KEF LS50meta, Salk, & Totem. 

Now go have fun! 

What size room? A lot depends on that

Listening arrangement to reveal imaging?

ON or IN bookcase, or just small on stands? You want to have your tweeters aimed at seated ear height.

Efficient or high efficiency speakers will help keep the integrated amp's power amount low, thus small: size, heat, weight, cost, and more options regarding placement. Small space: less heat is always good.

I have that Carver, amazing, for what it does, fits anywhere, but I would not recommend it for it's sound qualities, it has no features, no volume or balance, spring clips for speaker wires, thus even for a single source, you need a preamp, thus space needed for 2 pieces.

Staying small, wanting tubes, I just replaced my Carver with a wonderful sounding compact Luxman Tube Integrated, fits in or on top of a bookcase. SQ-N150. Has both MM and MC phono built in, keeps you down to one component. (limits: only 10 wpc, no pre-out/main in).

http://www.luxman.com/product/detail.php?id=33

I go out to a single self-powered sub for low bass extension, not 'real' low bass. Then to 'real' bookcase speakers (fit inside the shelf depth with no port or front port only).

It would be better to have an integrated with pre-out to self-powered sub, sub back to integrated main-in (or a tape or processor loop). That method reduces amp's need to make low bass, and small mains don't try and make low bass, which helps small speakers with no ports; helps you use less efficient small mains, allows a much lower powered amp.

Raven says low bass is about 65% of power needs, scroll down a bit here

https://www.ravenaudio.com/product/nighthawk-mk3-tube-amplifier/

Despite the advice about efficient speakers, I am getting away with using the least efficient speakers I ever owned (Wharfedale Diamond 225, 87 db) with the lowest powered amp (10 wpc), and a self-powered sub, 12", 800 watts in my small office.

btw, before I brought it up here, I hooked the little Luxman 10 wpc to my very efficient horns/15" woofers in the main system. It sounded great, good volume for my typical needs, but not enough when I want to blast bass heavy content.

 

according to your components, I strongly recommend B&W DM604 monitors. It's truly classic design and champion for asking price.

Define "Best speakers" please. Budget would help. Room size would help. Best speakers -to a degree- don’t matter, what matters is what your favorite sound signature is. Super fancy speakers in an acoustically challenged room is a waste of money as well imho.

Don’t overlook the Aerial 5T. It is similar in design to the Salk that Hilde recommended. 
These are great sounding bookshelf’s but are power hungry. If you’re going to use your Carver you should be in good shape. Not sure what your tube amp may be, but you can bi-amp the 5T too. 
I have mine hooked up to a MA 7900 (ss 200 wpc) and they sound fantastic for a little speaker. A little light in the bass but that’s the reality of a small driver.
While the speakers are well made, the stock jumpers really hold them back. I replaced them with some WW Oasis bi-wires ($90) and could hear an immediate improvement. Money well spent. 
Here’s a little rah-rah infomercial:
https://www.bing.com/videos/search?view=detail&mid=D5210292D83AF9C0A8DCD5210292D83AF9C0A8DC&...

Good luck with your move to downsize. The upside to downsize is there’s freedom in simplicity.