Amp and Preamp recommendations for Yamaha NS5000

So...soundorg just hired three people in Canada.  I am sure you will be able to get Chord gear up there.  
The bigger issue is that Ultimas are on back order for a couple months because of COVID 19.  They have had trouble getting parts like many manufacturers.  
Regarding Chord being difficult to work with, they did just change distributors in North America.  I had a great relationship with Bluebird.  I am off to a good start with Sound Org.  Both have been good to me and can’t say they have been difficult.  

From an amp perspective, a Chord Ultima 5 could be interesting for you.  300w into 8ohms.  The amp is less clinical than prior Chord amps.  Pretty darn neutral.  The error correction tech makes it pretty special and these are a really special line of amps.  I have a customer who has one for a pair of Monitor Audio Platinums.  
Pricing is just about right paired with a variety of tube preamps.  I am planning on getting an Ultima 6 Later this year to pair with two different preamps, the Art Audio Conductor and the KR P-135.  The nice thing is, you have flexibility with both units in terms of rolling.  I hear amazing things about the P-135, ironically with EML Mesh 45s.  The Art Audio runs 12BH7s and 6922s so there are plenty of NOS options.  
You could obviously use a variety of other preamps, VTL, PS Audio BHK, McIntosh c22, etc... and get a great result.  If you want a more energetic sound, a SS preamp will deliver that or you could go direct from a Chord DAC.  
I know you are in Canada.  Normally I would say I am happy to take all your gear on trade but am thinking the border may make life difficult.  No problem for the ARt Audio or KR gear, but a trade and Chord sale could be tough.  

There is a difference in sound between Pass’s class A vs AB stuff.  The warmer, more liquid sound is Class A where the AB stuff is less so.  You should not assume the AB stuff sounds the same.  Be careful and talk about specific models.  Note that poster above was looking at warmer amps vs his 350.8.