Looking for high power warming sounding tube amps

@smodtactical "but when I heard the CJ monos I heard the true mid range magic."

Hook, line, and sinker!   When your buddy let you demo them, knew exactly what was going to happen. :) 

My Quicksilver Mono 120s with KT120s (midrange) or KT150s (linear/transparency) fit the bill for the same reasons you are looking for. 100wpc.  I also have a Soderberg (recently) modded and upgraded Pass/Forte' now true Class-A 50wpc just to give you an idea.  Enjoy both for different reasons, but gotta say my tube amps are my fav when Im ready to really sit and listen to music and want that extra 15% of magic.  The upgraded Pass/Forte' Class-A not far behind. 

My QS have a bit more body, bigger transformers (4 of them, 2 per amp), with a bit more depth, layering, 3D sound than my Class-A Pass/Forte. Just to see what they could really do, on the QS M120s I upgraded the coupling caps to even better Mundorfs and upgraded the four main power caps to even better Nichicons. The amps really came into their own. My speakers enjoy the added bit of current.  They sound their best when driven by a nice tube preamp, I'm using a dual triode 6SN7 preamp. Add really good interconnects for source, and pre-to-amp, and ur there. Play with input tubes on the preamp and the mono amps for fine tuning.   

re: X350

@charles1dad I do believe that the higher damping factor (DF) is appealing and its effect on bass is desirable for many. In my experience it adds a “tightness “ to bass frequencies that I just do not hear when listening to actual live acoustic lower range instruments.

Speaking of damping factor and comparing - quite a wide range with familiar amps many here listen to. Its kind of interesting studying damping factor in different type amp designs.

With Pass’ different designs and comparing, the older X350 and newer X30.8, both have a damping factor of 150.

The lower power Firstwatt SIT3 is a lower damping factor of 30, and Firstwatt F8 is 40. Then we compare to the venerable class A Pass XA-25 bounces up to damping factor of 500.

While I look for some of that lower midrange bloom and upper mid-bass bloom myself hoping for a more realistic sound,

Noting my own QS Mono 120s, have a damping factor of 15.

The latest Quicksilver KT Mono amps have a damping factor of 20.

The ARC 160S Reference Stereo amp has a damping factor of 14.

The Deware SE34I.5 into 8 ohms has a reported damping factor of about 5.7

@charles1dad So again, what is the individual listener trying to obtain/achieve?

Exactly. Your post about the "snap" got me thinking about this more. I guess some like that unnatural ultra-fast snap of snare or kick drums or fast ping of a piano key. Not for me. While I’m not into sluggish playback either, finding that sweet spot matching the amp with the speakers in the right way, sure can make it enjoyable.

Individual-who, likes what:

• Listeners: I tend to look for posts and feedback on these audio forums by those who’ve played instruments and/or grew up listening in/around live music. Their brain has been shaped, knows what good sound is and can recognize it without even having to think about it :)
• Engineers: some focus primarily on signal-to-noise and flat lines on graphs, I digress - they usually don’t get it, and think they do.
• Hyrbrids: Individuals with a background in music who can also design and engineer amplifiers and speakers is a rare breed to look for.

Truly appreciate those who understand this balance and can design it and produce it for normal consumers to purchase. This community can help save/protect them by paying a little more for their products and services to keep them in business. 

@smodtactical Are the quick silver amps more fast and neutral and linear? Or more romantic, bloomy and warm ?

It depends on which output tubes you want to run and size of amps/transformers. The older version amps have changed some if you are looking at 20 year old amps.  

Changes with EL34/KT88 tubes with smaller amps and smaller opt transformers (Mid Monos) having more of that Classic sound like you get with CJ "Classic" amps.  The older (vintage type) collectible (MX-190s) run multiple EL34s, larger amps.  

As you move towards the newer generation amps (Mono 60s, KT88s) or running more KT88s (like V4s), adding more power, similar sound.  Split the difference some with KT120s in the Mono 120s if you can find a pair.  Kinda has the EL34 sound with more power with KT120s, sort of. Not exactly, each opt is different.  

Now similar to CJ new "Art Series" The transition to more linear/neutral sound you ask about comes in when running tubes like newer KT150s. More power, neutral, more bass. Less of the classic sound. If you truly need 100w, the larger amps with the bigger transformers can get you there if you are willing to go with more output tubes (V4s) or the larger KT120s, KT150s.

In 2022/2023 The new "KT Mono" amps from QS allows you to run a wider range of the opt tubes now.  The older gen amps tend to only run 1 or 2 opt tubes types, specifically. i.e. I can only run KT150s/KT120s (higher plate voltage) in Mono 120s, cannot run KT88s.  However, the new gen "KT Mono" amps quote ("accepts KT66, KT77, KT88, KT90, KT99, KT120, KT150, and KT170 power tubes and when ordered  with KT150s will produce 100 watts".) Gives a bit more variation for the type of sound you might want.  At QS, lots of other amps existed between over the years, with different sounds (8417 / 6C33C triodes).,  Seems the closing chapter is winding down to the "Mid Mono" or  the all new "KT Mono". Many others shows "DISCONTINUED" if you click on each on the site, as TBD coming out of th pandemic.  Hopefully some of those come back, we'll see.  Some nice used stuff out there too.