tubes and rock and roll, good fit?

I'd give serious consideration to VAC's new Statement 440 amps. I chose VAC (Phi 200) over VTL (MB 450sII) because I found more musicality, better control over microdynamics, and all around more lifelike sound from VAC.

That being said, Gryphon is what Andy uses, a point you should not overlook.

Musicians use tubes because of their musical overload capabilities.

If you really want to try out a tube amplifier, and see it rock out properly, the first thing to understand is that tube power is more expensive than solid state. The second thing to understand is that (with transformer-coupled tube amps at least) the bigger the amp the less bandwidth, due to limitations of the output transformers. Rock, like all other forms of music, demands bandwidth!

So the speaker is the real issue: in the world of tubes, there are two critical variables: impedance and efficiency. Low impedance low efficiency speakers are popular today because 600-watt transistor amps abound, but such are anathema for tubes **if you really want to hear what they do**.

So I recommend a speaker that is at least 8 ohms, and efficiency that is at least 90db. That way, you will be able to achieve satisfying rock in most average rooms with about 200 watts or so. Keep in mind that for each 3db of increased efficiency is the same as doubling your amplifier power- that is why in the industry amplifier power is often referred to as 'gold plated decibels'. If your speaker is only 87db, you will need a prodigious amount of power (+400 W) to make it fly, and its just simple physics that tube amplifier output transformers will not be full bandwidth at those power levels.

The speakers I run (since I play lots of rock and I'm pretty demanding, regardless of the music) are 97 db and go down to 20Hz so I can shake the walls with only 60 watts. Yet at the same time these speakers are as revealing as the best ESLs, IOW I'm not sacrificing any musicality for the increased efficiency- rather it seems to me that most lower-efficiency speakers are the ones sacrificing musicality for their lower efficiency...

Never a bad idea to look at what the speaker's designer uses....

Gryphon is SS, no?

I'd call Rockport and see what he says about running his product off any particular tube amp.

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!

Yes, tubes have a rock factor never incountered with SS. If you want the real crunch of a LP, then start with high power PP amps and fat sounding speakers. Bands like Tool and Alice in Chains sound awesome !! The mids just scream at ya. some purists my not like the in-your-face result, but i dig it !!