Low power tube amp for Sonus Faber?

A lot will depend on your room size and listening habits.
The speaker efficiency is about 88 or 89 db 1 watt/1 meter; on paper the speaker is rated with the sensitivity spec of 91 db. But because its nominally 4 ohms, this means that the voltage into the speaker will be more than one volt; hence the lower efficiency.
With tubes, the efficiency spec is a lot more useful!!

30 watts won't be a lot of power on this speaker. I would consider something with more power. The low impedance dip in the mid bass is not challenging to most tube amps (including OTLs) so I don't think you have any worries there. I would shoot for an amplifier with 100 watts or so- you could get by with a 60 watt amp, but if you play tunes like I do, you'll be running the amp out of gas.

I have a small room and listen mostly to piano, jazz, opera, classical, full scale symphony etc. 

If I crank up the volume, am I risking amp to clip and damage my elipsa? 

i really wanna get the amp, I’m in love with it. 

I bet that amp will never get out of 2nd gear in a small room even with the SF speakers, and it's doubtful you will ever use up the 30 watts unless you use your room for drunken dance festivals...30 single ended watts is a strong wallop of mojo. I initially used my 12WPC Dennis Had SEP amp with allegedly 91db speakers (they may have actually been closer to 89db based on Stereophile measurements) in a largish room, and the preamp (SS with lots of gain) had enough gain to drive the amp into clipping which I only did when wondering, "what does this amp sound like when clipping?" Music could be plenty loud well below the clipping point so I just enjoyed the crap out of the rig...switched to 99db speakers eventually (Klipsch Heresy III) which really are more appropriate for this amp, and use a lower output tube preamp. Now things can get way louder than I ever want it to with absolute clarity, well under the clipping zone.

Hi ei1001h,
I can understand your fondness for the Mastersound 845 as they can sound simply gorgeous with the ’right’ speaker match. You’ve received some good replies.
1. George makes a compelling point in regard to the load demands of your speakers in the difficult mid bass region.

2. I find it interesting that atmasphere doesn’t consider this to be a challenging issue (mid bass load ).

3. Mr. Garcia makes a keen observation that in a small room the 30 watt SET amplifier won’t be a limiting factor (he may be right given the circumstances ).

Is there any possibly to hear the Mastersound in your system prior to purchase? Obviously this would settle the issue.
Best of luck,
Charles

If I crank up the volume, am I risking amp to clip and damage my elipsa?

No.

i really wanna get the amp, I’m in love with it.

 Imagine putting monster truck tires on a British sports car from the 1950s- if you really want to experience the charm of such a vehicle, put appropriate tires on it. Same thing here- if the amp is the determining aspect, get a set of speakers that will do it justice. A more efficient speaker and maybe one with higher impedance as well will really help.