Ero,
With that budget, assuming that you can buy used, and that you wish to stick with tubes, I'd recommend the VTL MB-450 monblock amps. (Used prices are around $4-5K). These have enough power to drive the speakers with authority, and control the bass response. (Note, while the VTL MB-450s have very good bass response, in fact great for a tube amp, they are not quite as good as an equal quality solid state unit. But then again, an equal quality solid state unit will not have the benefits of tubes either, such as the nice mid-range that the VTLs have. Trade offs are a part of being an audiophile unfortunately.) I should also point out that the VTLs tend to run hot and will warm up your room a few degrees.
If you can expand your budget a bit (to around $8K), the tube VAC Phi 300 (150 wpc) stereo amp is about as good an amp as can be found, IMHO anyway. The bass is still a bit rolled off, (like the VTLs), but it is better in every other aspect than any other amp I have heard. (A truly reference amp, IMHO.) It too runs hot though, and will warm up your room several degrees.
For a solid state amp, I have heard that the BAT VK 600 SE (300 wpc) stereo amp is very good, and used it runs about $6K.
If you want the best of both worlds, and if you can expand your budget a bit, (up to around $7-8K), the hybrid Lamm M2.1s (200 wpc) monoblocks are great. (FYI, these are what I use with my Andra II speakers.) The Lamms have all the benefits of tube amps, (lovely mid-range and treble), and the benefits of a solid state amp (incredibly deep bass that is tight and quick). The only downside to these amps are that they tend to run very warm. (Not quite hot, but you're room will still be warmer by a couple of degrees.) And if you can find a pair of their successors, the M2.2s (220 wpc), they are even better (the treble is slightly more extended than the M2.1s). However, the M2.2s have been running closer to $11-12K used.)
As a side note, my friend and I compared his Lamm M2.2s to the VAC Phi 300 in his system. The Lamms have better bass (quicker and tighter) and better initial impact on percussion instruments (such as the keys/hammers hitting piano strings), than the VAC. But the VAC sounded sweeter in the mid-range and it bettered (very slightly) the Lamms in the treble response. (I think the Lamms are more neutral, but man, the mid-range bloom on the VAC is addicting.) I would be hard pressed to pick between the two actually. My friend decided to stick with the Lamms because of the bass response, and also because the VAC ran even hotter than the Lamms, and due to the potential cost of retubing (probably $1,000.00 or more if using NOS tubes). But it was a very close to a toss-up as to which amp was better. (IMHO, neither is better, as both have their own strengths and weaknesses.) By the way, I am being incredibly nit-picky about their weaknesses, as both amps are fantastic, and I would love to have either!
My two cents worth anyway.
