Whats the FATTEST sounding Tube amp to warm up Lean speakers?

What would you say is the fattest, warmest fullest sounding Tube amp to fatten up
Merlin VSM's?

They are 8 ohm, and easy to drive. 30wpc would do.

From my understanding, through reading here, the Famous match with AtmaSphere s30 actually doubles up on the natural detailed and spacious yet lean character of the Merlins.

Which Amp would do the opposite - be a little forgiving and sweet in the higher mids and fatter and fuller in the lower mids?

I have a pair of Mid Monos,  and they rock with KT88...   I have used them with several speakers ...  big and bold but still have great mid and highs.  
Any older Conrad Johnson tube amplifier within your budget will give you what you're looking for. Expect syruppy mids but less crisp highs and slightly bloated lower bass - depending on the matching with your speakers, if you're willing for the trade-off.
Whatever tubed amp you choose, load it with NOS British valves(Mullard/Brimar/Ediswan/Genelex/etc).  If those don't warm/sweeten/fatten things up enough, swap it's resistors out for carbon compositions, and/or- it's coupling capacitors, for oil in paper types.
I'll go as far to say it's not the tube amp but rather your choice of tubes. Vintage little Mullards are extremely warm sounding. Vintage Tung Sol 6550's solid plates are warm like Mullards but with the EL34's glorious mids that are known for but with a lot more low end and power. I was never a fan of current production tubes. I had the Octave V70SE and later the V110 with a black box. I even had the V40SE for a short while. All were good but as you move up the line you gained more 'control' of the music.
Agreed on the NOS Mullard EL34's. They are what I have in my Shindo Montrachet and I couldn't be happier.
The late designer of Merlin almost exclusively used Joule-Electra OTL amps at trade shows. You might want to contact Rich Brkich of Signature Sound, as he knows Merlin speakers as he worked closely with the designer.
Sure- the Jouls is known to be a favorite match by the designer, however, im trying to counter the speaker's philosophy here, so it is my thought that the Jouls is actually going to emphasize the leanness of the speaker, not counter it. Or Bobby P wouldn't have used it.
I for one would not characterize the Quicksilver midmonos as "fat" by any definition of the word but it very well may flesh out the lean character of the mid/upper bass of these speakers which is where the issue lies IME.

Agree, that many stock vintage tube amplifiers could be characterized as "fat" particularly in the area of bass. vintage McIntosh and Conrad Johnson certainly come to mind. I also concur with Rodman999999 regarding those vintage British tubes to help fatten up the presentation. I know a LONG time Merlin owner that went from Joule 100 watt monos to a Roger Modesky Music Reference RM9 after the demise of Joule-Electra. Last time I communicated with him he was quite happy, something to consider as well. 
The most popular speaker for many years with our M-60 amplifier was the VSM. Very nice match and we showed with Merlin at several CE Shows.

But I would not call the amplifier fat sounding (which usually describes an excess of 2nd harmonic distortion which our amps tend to lack). It just sounds natural. 
The Atma-Sphere OTLs and the Music Reference RM series of amplifiers are not going to "fatten" the sound, they are very flat and just get out of the way. As I mentioned on your other thread old Cary amps and as also recommended here old Conrad Johnson amps will be more suitable, but I also think you're not making the most of your VAC Avatar. Sure it's not  syrupy like some classic tube amps, but it is real. I can't see an amp speaker mismatch because Merlin speakers play well with lots of amps, but I'm not your ears either.
Getting tomorrow an eq i ordered, see what that does in small touches, a db here and there can maybe fix it.
Sure- the Jouls is known to be a favorite match by the designer, however, im trying to counter the speaker's philosophy here, so it is my thought that the Jouls is actually going to emphasize the leanness of the speaker, not counter it. Or Bobby P wouldn't have used it.
I don't agree with this statement at all!
Bobby was not going for a lean sound, and I've not had anyone report that to me when using Merlins.
How do you have the Merlins set up? Are they firing into the long dimension of your room or the short dimension? Normally to get the best bass, the speakers will be firing into the long dimension.

Are you using the BAM? If no, it will sound lean.
Did you check to make sure the phase is correct? If one speaker is out of phase with the other, the bass will be gone. Try reversing the phase after playing a track with good deep bass and see which way has the best bass.
Often you can move the speaker back, closer to the rear wall and get bass reinforcement. You may lose some dimensionality though.  Similarly, the listening chair can be moved back to a room boundary to reinforce bass.

Some amps just don't play bass all that well and I can't speak for what you have right now. But as you know, Bobby designed the speakers to be easy on tubes and he really liked OTLs- on the right speaker they can play bass better than most tube amps!
Finally, long speaker cables and tube amps don't tend to play bass as well. Keep your speaker cables short- 8' might be the longest you can run and 3' would be better. Make sure your connections are tight too.

Any of the CJ Premier series... 8 or 12 mono, the 11 Stereo.... I miss my 8A's, although my back feels otherwise. If it were me, I'd go with the one that will drive your speaker. A bit off subject, but the Premier 16 is also a little honey. 
Hello Mr. Atmasphere (what is your name?). Glad you jumped in!

I did all the things you mentioned. Well, i need to clarify.
The VSM don’t really lack that much in the low end. They are quite surprising down below 50hz for a 6.5" driver.

Where they do lack, in my personal opinion, is the low mids. Anywhere between probably 400 or 350 down to around 60.
From many years working at the recording studio i have quite some experience with different reference monitors, all claim to be flat and non hyped. They all have a lot more information in that area. is it "True"? i don’t know what truth is, i just want to sit back and have some chesty warm honey in addition to the great high freq detail and wonderful space and field that the VSM do provide, Thats why i insist on finding a solution with them and not without them. I want to tailor them to my liking.
To me their balance right out of the box is bright and lean. I don’t have to mix on them so i allow myself to alter their "Truthfulness" and make them my own.

That is the reason i am looking for other parts in the chain to bring me closer. That’s part of the fun in loving to listen to music. We have different listening tastes just as much as we have any other taste i suppose.

I heard amazing things about your Amps and i am close to trying your s30. However you say its not going to alter the freq balance of the speaker itself. But i still want to try it. Most of my peers in the recording and mixing world are completely unaware of the Audiophile world and so was I until recently, so i came here to learn.

I have 35 years of obsessing over Studio gear and obtaining it, but The audiophile world is new for me. As they say, "the cobbler walks barefoot". I made many records and invested in the recording aspect but never in the "listening for fun" aspect,

So here I am, trying to tailor for myself the perfect listening situation with less consideration to "Correctness" as it were.

A word about Bobby RIP. I think he was a total genius, and i admire his speakers. I Just allow myself to "Bend" the method, just like I abuse gear at the recording studio to suit my taste, no 2 people hear the same...

Thanks again and i would very much like to hear your input, as, again, Im new here,

Cary SLM-100 amps are very warm and fat sounding.  Conrad Johnson MV-45 and MV-50 have a similar sound but half the power.
Agree with several responders. Old McIntosh or Conrad Johnson tube amps with English nos tubes. Good luck . 
just an opinion but i’d personally move into a more neutral loudspeaker opening up countless electronic choices. i don’t think trying to fatten up a 6.5” driver is a great idea but we’re all different. fwiw
4425- The Merlins are a marvelous example of detail and space. a little warming up in the low mids is all i need. Otherwise perfect for my listening levels and listening position. I don't want to start a goose chase. IM happy with 80% off what this speaker can do...
For the money you cant beat a Bob Latino VTA ST-70 with a set of Genalex KT-66's. I run this exact amp with a stacked Advent setup I get that big fat sound you are looking for.

Friends that hear cant believe it is a 35 watt per channel amp. Its really a site watching peoples jaws drop when they hear it.

You don't need spend a ton a money to get a great sound. 
A Octave with the 6550 tube might do the job.
Although not sure how warm a sound you want.
All the best.
@ salectric- I’ve been using a Cary SLM-100 pair, for close to 15 years now. The last thing they are is colored(warm/fat sounding). Cary offered Jensen’s copper foil/PIO caps, as an("upgrade") option in their amps, but- Carys are not known(typically) for coloring the music they reproduce. Of course(again), tube choices can make a big difference.
OP, you didn't mention what preamp/amp you currently have in your system but if the equalizer did not solve your issue, a tube preamp can also add lots of "syrup" to the mix, sometimes even more than a tube amp.
Be careful what you ask for with the Merlins.  Along with fat, full and warm you most likely will also get slow and syrupy.  I have 2 pairs of Merlins and have run them with several different amps, including some older CJ amps.  With Premier 12's and a Premier 16 pre, for example, the sound I believe was as you describe you want.  But along with warm and full I did get a much slower sound.  Warmer tubes, like Mullards, accentuated it even more. 

Currently I'm using an Atma S30 with one pair and a Pass Int 60 with the other and like both more than the older CJ sound but that's me.  I don't believe you'll get to where you want to be with an OTL, but with Pass you might.  See if you can find an older Pass Int 30 unless you have a large room or play loudly.  Then the 30 will be under powered.

Good luck.
Interesting. How do you find the sound difference between the Atma and the Pass?
I agree with much of what has already been posted.  Finding the right mix per budget, I would aim a little higher on the power side to provide the dynamic headroom.  
I heard amazing things about your Amps and i am close to trying your s30.
Usually people use the S-30 with the TSM. The VSM needs a bit more power so the M-60 has been the preferred amp for those.
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What about slightly Under Biasing the output Tubes? Would that take some of the "Bite" off?
Would that damage the Tubes or amp or anything else?
may not suit you but the price of ARC ref75’s on audiogon have to be one of the best deals i’ve seen. a truly great tube amp with plenty of mojo.
i’m no ARC fanboy but bought one to try out and very impressed and i’ve had some great amps. btw moving the speakers closer together increases mid bass output just as closer to back wall does the same. i bet you already knew this. good luck
just had a thought. a used accuphase integrated amp would give you tone controls almost guaranteed to be centered at 100hz(bass control)which is ideal for midbass enhancement. overall going to sound great as well. 

I bought a pair of Merlin VSM speakers from Bobby in 1999-ish... I'd have to check the receipt to remember for sure.  He upgraded them once and they had better bass as a result.  In 2001, I bought a Joule VZN-80 amp.  Why?  Well, my wife and I went to the CES show that January and I'd heard the Joule stuff with the Merlins.  Hear that, like that, get that... It wasn't a hard decision when you've heard the solution.  Pay The Man. 

I am not an expert... but I do know the Merlins are a "damped" speaker design.  They don't need help from an amplifier with a high damping factor and tons of feedback to control the low end.  If you match an amp that is more inclined to low end control (high damping factor) it may sound "lean".  "My Merlins" are not "lean".  

My Joule VZN-80 has a dial to adjust feedback.  There is a reason why it's never been on anything but "all the way to the left"... ZERO FEEDBACK. 

If your amp is trying to bully your VSMs with too much damping, it will hide the magic. By the way... that BAM module makes the midrange you seek even better since it filters frequencies that driver can't produce anyway.  The BAM doesn't just help the low end... it also helps make the speakers more accurate by not asking them to do things it can't do. 

That's one thing I do remember Bobby telling me...
I'm surprised no one has mentioned HH Scott tube gear. Especially when people are mentioning Dynaco. IMHO Scott absolutely SMOKES Dynaco ST-70 in every way possible. If you're looking for that fat tube sound, and want to hear some "magic", or "emotion" in your music. Especially with a bright, or lean speaker. They fatten/smooth them right up, and are just amazing to me. I just picked up another one this past week actually, a restored 340B receiver from 1964.

First time I heard the Dynaco. I kept thinking. "This is it? This is what I've heard about, by so many people? Where's the magic?". And this was on a nice, and very rare, vintage pair of Jensen's I went to look at, along with the Dynaco. I didn't buy either. But oddly enough, the same seller had a B&K ST something, or other. I think it was a bigger model then the original 140. On the same Emotiva preamp, but playing through old KLH Model Ten's (which I've never seen before, or since), that blew me away. And my dumb arse, being new to this at the time, walked away without the KLH 10's that he was selling for only $75. I'm still kicking myself for that one.

I would also think about a parallel SET amp that's fat sounding (not a Mastersound Box obviously), or maybe an 845 SET. Some of them are fat too I've read. The parallel SET from Musical Paradise (forget the model) is supposed to be a little on the fat side, but have a really nice "you are there" sound. And I wouldn't be surprised if they had a good return policy. They're known for great customer service. It's a 55 watt per channel Integrated one. Oh heck, hold on, I'll find the link. Here you go. 


Gets great reviews, at least from the few I've read, and again. The company does too. 

Whatever you decide. Good luck with your search, and I hope you have a Happy Thanksgiving.
Andy B. 
I never found that I could enjoy that speaker. To me they were bright and forward. The Esoter tweeter I believe. Not sure they are worth curing. Easier to sell the speaker and replace. Lots of classical music fans like them because you can play them at low levels and not feel like you are loosing much. 

These are my opinions based on owning a pair and pairing them with Joule Electra and Atmosphere and even Sophia Electric 300B ( without the Bam ) 
@dumbeat- Regarding under-biasing: That will somewhat reduce your dynamics and may soften what you’re calling, "bite". Trying that won’t hurt anything, and actually increases tube life, though- at the cost of fidelity. https://wallofsound.ca/audioreviews/amplification/output-tube-biasing-an-introduction/
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The Mid Monos are designed around EL34 and that's what I'm using now...

KT 88 does sound "fatter" ,  but it's always best to have a speaker that appeals to your listening tastes rather than trying different gear to "tune" them 
Thing is this speaker appeals to me in many ways but not all.

Since this is the biggest most cumbersome piece in the chain, im trying to adjust to it before i give up and continue schlepping more speakers that may or may not work in my room... But essentially of course you are right...
I've been to many shows and always very impressed with the Merlin's... I've heard them driven by Joule and Atmasphere and would not venture from those two brands based on what my ears told me.

Good luck.
I will say that Bobbie used the Music Reference RM-9 in many of his industry shows. There are many Merlin/RM-9 owners out there. 

Lets hear from you   :)