Tube Monoblocks for JM Labs Electra 927 Be

How much power do I need to run these in a smallish room? Currently I am using a MF A308, about 150w/ch and the volume never gets above 1/4. They are rated at 90db sensitivity, but I have no idea if they have any nasty ranges with low impedence and bad phase shift, i.e., I have seen no curves.

What amps might be good? I have heared that 308b amps are wonderful, but replacing these tubes is very costly. I don't want to by alot more power I dont need, since tube amps cost more per watt. But I want that dimesionality and soundstage. I would probably keeo the A308 for now and use it as a preamp.
Without knowing your budget I'll throw a couple out there.

Rogue M150's
Theres a nice demo/used pair of Thor 30 watt monos on this site. These have plenty of power and sound awesome.I easily drive a pair of Kharmas ( 1.0 ) with my Thors'
90dB sensitivity means nothing for these power suckers.
Powerful VTL amps MB180 or larger are in my mind or you can biamp tube and ss. Also Mesa Baron amp have an ability to drive a difficult loads such as JM Lab Electra.
As an Electra 926 owner, I can tell you that my 45W CJ tube amp in my 14x15 room is just fine. From what I saw in Hifi-choice, the impedance dips to 3.5 ohms at 50 Hz or so but the phase isn't bad and the senstivity is indeed higher than average for both 926 and 927s.

However, I would say that 30W is a minimum and even then, you will need to keep the volume somewhat under control.

You only want monoblocks? That will limit your choices significantly but if so, the Cary six packs may be plenty of power and sound great. Arthur