What To Replace A Pair Of Lamm Ml2 Monoblocks With? Need More Power

Jadis JA80Mk2 or JA200Mk2 would be a good match to Vandy 5's. 

Vandersteens are awesome but they need some power to be at their best. The fact those 5as have a powered bass module, means the absolute power required is no where near as high as it could be. 
You have a few options.  The room is large but not crazy and those aren’t difficult to drive.  
You could look at something like a BAT Rex 3.  Two issue with BAT is everything needs to be BAT or it loses a lot in terms of sound quality so you would probably want a BAT pre as well.  They use the same tube but it is also a parallel SET design which could be problematic.  SETs don’t like being driven hard.  One upside is you can get this on a 60 day demo from Music Direct.  My hunch is a 45w push pull will outperform this when driven hard but I mention because of the tube type.  
Another really interesting option is Jadis.  It is a KT120 based solution but is going to have oodles of power.  They have a 150w class A/B amp that is $16,500.  They have some high powered Class A Monos that are in the $30k to $40k range.  Gorgeous equipment and a sound that is somewhat legendary.  

Angstrom is an Italian brand and the Stella line of products is incredible.  The SSA 100 or the SMA 150 would be A+ choice.  $17k and $32K respectively.  It is Class A, zero feedback and uses EL34s so it has a very appealing sound.

The final (and IMO best) option would be the KR Kronzilla DXL Monos.  They are 140w push pulls using the Kronzilla tube and are also Class A with zero feedback.  These will be closest in terms of sound to your Lamms I think other than the BAT, but the BAT seriously might struggle.  
I am a KR dealer and am getting ready to sign up for Jadis and Angstrom as they are awesome lines.  I have no relationship with BAT.  

I know these threads about suggested gear tend to be all over the place, so I’ll ask: Has anyone used the Vandy with Ken Stevens’ amps? He makes a stereo version that isn’t crazy money, probably within the zone of the Lamm’s value used, pricewise, depending on condition and tubes in the latter. I haven’t heard any of his amps, but know a few people that use them whose views I respect. He finally got a website too. At least the OP will stay in the zone of one man operations but you’ll lose the charm of the mad  Russian. :)

I’ve heard The Angstrom el 34 push pull amplifier and the Jadis el 34 (Not the KT 120 based model mono blocks). No question about both of these brands are exceptionally good sounding, very natural. You re getting into a much higher price range and I’m not sure if there’s a budget ceiling. By comparison the very well made Quicksilver is far more affordable and I suspect quite good sounding utilizing KT 150s. There are numerous good tube amplifier possibilities. I have heard flattering comments in regard to the KR Kronzilla amplifier .
Charles

for what it’s worth, i only recommend and fawn over things I have actually...heard..

When I bought my 5a from Randy at Optimal is Santa Monica, he had two demo pair. One plain Jane maple, another in a wild Rosewood at his house in Malibou. H e told me to go listen to the Rosewood. He was using the Quickie 120 at home ;-)

fun, enjoy the journey....