Tube Integrated With Clarity

you have described the newer McIntosh tube sound, not to be confused with the older warmer/mushier sound. You may want to consider one of them in your short list. Used probably but there are lots of them out there and they hold their resale value better them most. 

Bryland, I have the Audio Hungary a50i. You should be able to pick one up under $4000 used.  I owned a LTA preamp and thought it was very nice but would not call it as tubey as I tend to prefer.
 

I also own some modern Conrad Johnson and prefer the Audio Hungary. The AH bass is some of the best I’ve heard coming from a tube integrated amp. It’s deep, big, solid, has tone and moves air, very impressed, maybe partially due to it being class A. The detail and information it pulls is just as impressive as the bass.

The amp is very fast and does not stumble no matter how complex the music is. It also plays every type of music you throw at it, the CJ can’t do that. Got to say this is my favorite integrated amp I’ve ever owned, For me this one is a keeper. Good luck on your search. I’ve always felt the preamp section in integrated amps are the weak link not so with the AH from what I’m hearing.

I really like the LTA gear and the guys that run the company. My son lives right outside DC and maybe 10 minutes from their shop in Takoma Park, MD. If you are anywhere close, you should visit them in person. I did that and spent a few hours talking about their gear and listening. I met most of the folks working there, but alas, no David Berning. I am continually watching for their Z40 integrated used. Until then my Luxman L505 uXii fills the gap pretty well. One thing I like about their amps is that they drive their tubes very conservatively and project extremely long life for those expensive NOS tubes. good luck in your hunt!

Ayon isthe best built excellent sounding and use world class Lundahl transformers  and chokes ,and a very nice machined case , not cheap sheet metal like most ,

it is microprocessor controlled which monitors each individual power tube 

which tubes last much longer then then just averaging all power tubes combined 

just hit a button if a tube goes and ready to go , the spirit 3isvery good and uses Mundorf Preamp coupling capacitors on the output , made in Austria not China 

C core transformers are the world standard for top Tube Amplifiers , toroidal  transformers Never in Any world class tube product .

Wait, correct me if I am wrong here because I have limited experience with tube amps but when the OP says he wants something “very fast”, is he barking up the wrong tree with tubes? Articulate and smooth I can buy in to but “ fast”? You tell me.