Conrad Johnson Premier 12, how powerful?

The Opera Callas are 8 ohm. I'm afraid I don't know about the impedance curve. My room is fairly small and I listen mostly at low volumes, but I've found that low volume listening is where you appreciate power the most. So far with these speakers I've auditioned the Mcintosh 2275, which is rated 75 wpc, and found it anemic. Then I tried the ARC 55 wpc integrated, and that had very good power with these speakers. Go figure. With the CJ, 140 wpc of tube power seems enormous, so I'm confused as to why several sources warn about matching this amp with inefficient speakers.

But thanks for your responses. I'm fairly convinced that these would be fine with my speakers.

My memory of the CJ Premier 12's is that they had plenty of of guts but were not the quickest amp. They are a more traditional tubey sound compared to the latest offerings from CJ, or most other manufacturers of tube amps. Beautiful look and sound, and they seem to hold their value. Probably a classic. I'd recommend owning them, at least for a while to get to know them.
Art

Have you purchased the 12's? If not, shop for 8s' or 8a's. These 275 watt top of the line amps can often be had for $4000.00 to $5000.00 here on audiogon (original $ was about $18000.00). For a few more dollars you'd be getting alot more amp.

Hmmm... Now I'm discouraged to hear that the 12 is not quick. My impression from the reviews was the opposite, that they are quick, and quicker than previous CJ gear. I've only heard the MV60SE from CJ, and loved the quickness and overall presentation, but thought I could do better for the money.

Speed is relative and mostly a function of speaker/amp synergy. Coincidentally, I just got off the phone with Ed from cj and one of the subjects we touched upon was the speed improvement realized by using Teflon capacitors. So, given that you thought MV60SE was fast enough, I'm sure you will find the same with the Premier 140; but if ultimate speed is of concern, audition the cj LP140 with the Teflon caps.