300B SET or EL34 SET

I understand completely.  When you hear something that you love, you want nothing else.  Also get that everything in Europe is more due to VAT.  

I couldn't find an impedance measure on those speakers either but generally speaking, Tannoy's are generally pretty tube friendly and I know they are brilliant with the Art Audio amps.  

This is interesting though, I just did the calcs for your reference ATCs.  If the ATCs are 85dB and receiving 35w of power and this was plenty for your needs, that puts your peak output at 98.7dB in normal listening conditions.  Listening position 2.5 meters from the speakers and the speakers are near the wall (~1M) but not in the corners. 

In comparison, the Audion EL34 SET is 12w into a speaker with an 89dB SPL, it is 98.1 dB of output.  It is a touch low compared to ideal scenarios but .6dB in output is not a lot. 

I was just running a speaker with an 83dB SPL at an audio show with a 45w amp.  I could still hit reference levels and it did sound good.  Now, don't get me wrong, I was at close to max volume and my speakers were near the corners of the room which helps enhance the sound.  But it would get loud in a 4 meter by 7 meter room.  Way above normal listening levels.  

What does the return policy look like on the Audion?  If you really like it...might be worth rolling the dice.  Have you heard it driving your speakers?  I would say with confidence 8w is not enough, but 12w is close.    Do you mind having the volume nob turned up above 50% most of the time you are listening?   There may be moments that you won't love, but 99% of the time you should be good.  

I tought my Tannoy Legacy Eaton at 89dB sensivity would be too hard for the 300B amp to drive

@simna  And you were correct. In reality a Push-Pull EL-34 based amp will be barely enough power in most rooms if this efficiency is correct!
SETs are simply out of the question unless your room is the size of a large closet. Something to keep in mind about most SETs: unless they employ feedback (and most don't) the distortion starts to take off once you reach about 20-25% of full power, so if you really want to hear what the amp has to offer (unmeasurable low distortion at low power levels, good for 'inner detail') then you need a loudspeaker with enough efficiency to allow that to happen. A 300b-based SET will thus need a loudspeaker of about 103dB or so in an average sized room.

European rooms on average tend to be smaller than American listening rooms, so you might get away with an SET if your room is really small enough.

My listening room is rather small, 4.48x3.96 meters and the hight is 2.62 meters wihch is aprox. 14.7x13 feet and 8.6 feet high. 
I'm sitting aprox. 2.5 meters (8 feet) from the speakers which is placed  40-50 cm (1.3-1.6 inches), toed in, from the wall.

I can't test the amps with my speakers because there's no dealer selling either the more expensive Tannoys or the Audion amps in Sweden. The two Audion amps the dealer had were trade-in. The Silver Night should the dealer keep for himself and the EL34 was already promised to another customer. And this more than a month ago, so they will not even be in the shop by now.
So if I wanna buy Audion I have to buy it from abroad. From Denmark or directly from Audion in France. Return policy? Don't think so.

The Chinese looked at what westerners were willing to pay for vacuum tubes, therefore, they put lipstick on a pig, used names of historic brands like Western Electric and call them replicas, put them in fancy presentation boxes and coated the internal and change the shape of the glass....and charged a premium price. Clearing targeting the North American market.  The tubes sound okay for new production, but can be bettered in most cases by NOS / OS tubes.

Look at a 300B + 845 or 805 tubes amp. 

You can have the 300B sweet midrange and glorious 3D image with great bass and dynamics (if you dont match it with extremely difficult to drive speakers). 

I have a Line Magnetic LM-508IA integrated with 300B and 48W per channel and it blew away a VERY nice class D amp I still have (in a box), even in fields where the class D amp should be better like dinamics and detail. Not to mention the much sweeter middle frequencies.

My speakers are 90 Db sensitive and 6 ohm of impedance, with minimum of 4 ohm and the LM508 drives them with incredible authority. 

I've had a cheaper EL34 push pull integrated, but the LM508 is completely  on another league. Its not cheap, but an incredible amp.