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

Curious which Conrad Johnson amps in particular have that "Syrupy" sound

Maybe just introduce an equalizer in the chain?

Sure- mentioned earlier that im trying it tomorrow

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.