Tube amps and speaker ohms


In your opinion , do push pull amps work better with 8 ohms or 4 ohms. .I am under the impression the lower the ohms, the more power is demanded from the amp....Another question, are there low powered SET amps ,and high power SET amps?
I'm looking at a 40 watt 845 tube amp for my 8 ohm, 89 db speaker.. just cked the Thor has a 86 db W18 midwoofers(2 per cabinet) and a 88 db tweeter. Will an 845 amp rated 40 watts be able to drive the 86/88 db speaker? With authority, bass, mids, highs, in dynamic sound stage? Synergy? Or poor match?
bartokfan
>>05-21-07: Atmasphere
Anytime you are investing in tube amplifier technology, that investment will be best served by a speaker that is at least 8 ohms or more.

Tube amps, with rare exception, have reduced performance into four ohms. <<

So, it seems that in general, Tvad is correct. Even though the Atma-sphere MA 2.2 may well drive the Woodmeres 4 ohm impedance to acceptable levels, the inference is that it would drive the Defintion AFI with 30 ohms impedance a helluva lot better. Furthermore, the 60 day in-home trial of the Defintions are a huge plus. Almost essential. So now will anybody give me their impressions of the "sound" of the Zu Definition, since there seem to be divided camps on this issue?
Thanks.
If you have the patience, my suggestion would be to audition the speakers in your home to get the best sense of their sound and how they would work in your room with your equipment.

Otherwise, there are many thorough reviews that describe them pretty well.
This has been a very interesting thread.......

Having said that, my Primaluna PL2 with KT88's, 40wpc, has no trouble driving the Proac D15's, 88db, to louder than WAF levels in our 15 x 30 x 10 room.

Bartokfan,
Did you ever bias those tubes?.....