If I may make a suggestion, (or two):
Try the hybrid (220 wpc) Lamm M2.2 monoblocks.
Two of my friend both use these amps, and one of them uses the Rockport Antares speakers. (His system is the best system I have ever heard, bar none.)
We have directly compared his amps, in his system, against several other amplifiers, including:
Kora Cosmos (100 wpc tube monoblock amps)
BAT VK 150 (tube monoblock amps)
Manley Neoclassic 250 (tube monoblock amps)
VTL MB 450 (tube monoblock amps)
DarTZeel NHB 108 (100 wpc stereo solid state amp)
VAC Phi 300 (150 wpc stereo tube amp)
The Lamm was easily better than all of them, with two exceptions.
The DarTZeel was very good, but underpowered, especially in the bass response. However, it is a very good amp, with a great mid-range, which was the equal of the Lamm. However, the Lamm was better in the treble, slightly, and much better in the bass response. So while the Lamm was better than the DarTZeel, it was not "easily" better.
The VAC Phi 300 was as good as the Lamm M2.2s in some aspects, better in some, and not quite as good in others. Specifically:
The mid-range on both were great. (The VAC had a bit of tube bloom, which while not as neutral as the Lamm, was intoxicating and I consider them to be equals.)
The treble on the VAC was better than the Lamm actually, which surprised me, as I have never heard an amp better the Lamm in this aspect.)
However, in the bass response, the Lamm was a bit tighter and slightly deeper than the VAC. However, the VAC was very good, in fact, I'd say it was great for a tubed amp. In addition, the initial attack of percussion instruments, (i.e. The initial impact of drum stikes, as well as the initial key stroke of piano notes), was quicker on the Lamms. Overall, I would say that the VAC Phi 300 and the Lamm M2.2s are very close, and for me, about equal. (My friend loved the mid-range of the VAC, but just could not quite get past the slight lack of bass response and the slight lack of quickness, so he kept his Lamm amps. Having the Antares speakers meant that he had wonderful bass response, and the Lamms allowed this aspect to shine through.)
So, my first suggestion is to try the Lamm M2.2s. (And if you do, I also suggest substituting some nice NOS 6922 tubes for the stock Sovtek tubes. Each amp has only one tube, so tube rolling is both quick and easy and relatively inexpensive.)
My second suggestion is if you really want to try a tube amp, to try the VAC Phi 300.1 (the upgraded version of the amp we auditioned). If you don't need the last little bit of bass response, this amp will serve you very well. (Better yet, if you can afford it, is to buy two of them, and bridge them to use as monoblocks, which according to another audiogon member who does this, solves the slight lack of bass response, which would make these already great amps, even better! Possibly even the best?!!!)
My two cents worth.
Good Luck in your search!
