Kinki studio EX-M1, EX-M1+ differences... vs Denafrips Hestia/ Hyperion combo?


I've been reading up on some Integrated Amps and Pre-Amp/Amp combos lately but have some questions.

The following is an excerpt from SoundStageHifi:
The original EX-M1 was introduced in 2017. The newly updated EX-M1 — without the “+” — costs $2398 and includes, among other things, changes in the power supply, capacitance, and the volume control, the latter now using a MUSES72320 controller instead of the previous relay-based control. The EX-M1+ is essentially identical to the upgraded EX-M1, but adds a preamp-stage output and a home-theater bypass to entirely bypass the preamp stage.

That last sentence has me a little confused. 
"The EX-M1+ is essentially identical to the upgraded EX-M1" - What is the "upgraded" EX-M1?  Does this mean that the latest version of the EX-M1 has all the updates that they just covered preceding this statement?

The 2nd half of the statement says " but adds a preamp-stage output and a home-theater bypass to entirely bypass the preamp stage." - You'll have to excuse my ignorance.  Does this mean that I can add a pre-amp in the future and use the EX-M1+ as a Power Amp?  Also, does this mean that I cannot add a pre-amp to the EX-M1 (non-plus)?

At this time, I don't have hard to drive speakers, and I don't foresee having something like that anytime soon, so I was also considering the Denafrips Hestia/Hyperion combo.  I haven't seen any reviews comparing these 2 company's offerings... any feedback is appreciated.

jwlaudio
@jwlaudio 

If all of those new amps in your stable are all single ended you may be disappointed with the BHK preamp.  Both myself and several friends found that when run single ended the volume control makes a great deal of noise when used in either direction.  The only way to mitigate it at all is to have fully gain and triode matched 12AU7 tubes which pretty much limits you to new production.  I had no luck at all with 6 or 7 volt tubes over the four years I owned mine and found it's best mate to be the BHK amp and I tried many. 
@jackd 

Thanks for that.  Why do you think this is the case?  I have thought about buying an XLR to RCA that boosts the voltage a little bit so I can use the balanced interconnects.  If I build another Nelson Amp Camp Amp, I could have an amp with balanced outputs in dual mono configuration, but the F8 and this Yamaha is noticeably better, at least to my ears.  I hope they send me new tubes, PS Audio is building my BHK pre right now, so at least the unit is new production.  It's been like 3 weeks already, hopefully they will finish building it and send it out to me soon.
@jwlaudio 

Not sure but something in the way Bascom designed the volume control circuit.  Just know that between a friend and I we tried three different units and almost a dozen SE amps.  If it causes a problem at least you have the 30 day return.  
@jackd

Thank you.  I have 4 amps, all with SE inputs so if that volume control is unbearable, I guess I'll have to think about returning it.  I do use the volume control often since I use this system from multiple sources.  I really hope that it works out for me though.  I've been hearing such good things about this BHK Pre.
@jwlaudio 

One way around it once you figure out the "sweet spot" volume for each source is to mute before changing the volume level then un-mute.  Anyway even though it doesn't have all the remote conveniences and input options of the BHK I much prefer the sound and lack of quirks with the Supratek Chardonnay at a far lower price.  Same is true of the Don Sachs preamp.