Yep. With a 4x12" you can have the same SPL you get with a 1x12" whose sensitivity is 6 dB higher.
Feel free to turn the trimmer clockwise as long as you not perceive any distortion. I'd advise you to use a sinusoidal signal (it's easier to perceive new harmonics), and you'll have to do it with the 4x12" and at rehearsal volume (or you won't be able to hear a contingent distortion.
HTH 
one silly question. ...in a thread someone uses the camplifier 360 (2x180 class d power amp in a 2x8 cab) and said that there is not enough power with the distorted sounds when playing with a drummer. In the other hand the ambrosi with only 50watt (class a/b amplifier) does the trick. Does the nature of the amplifier class d vs a/b play a so crucial role?
There might be some differences, but - provided specs are measured the same way - the most critical factors are certainly the cab's impedance and, especially, the cab's sensitivity.
Note that the nominal impedance of a cab is by definition measured @ 1000 Hz. But this doesn't say anything about how the impedance varies with the frequency. Two cones might exhibit the same nominal impedance but one of the two could sound louder at the most critical (perceived-volume-wise) range of frequencies.
Another important factor is the cab's directivity: the more beamy and focused its diffusion, the more difference you'll hear when moving far from the front.
Note that the cab placement may play a critical role in this (see my previous answer).
The room plays a role as well: its resonances might emphasize the drums Vs. the guitar (if it's boomy for example).
Another factor is the profile you use and how you tweak it: if its sonic spectrum tends to overlap with the drums (or any other instrument), it will be perceived weaker in the comparison (it won't "cut the mix"). Under this aspect, also the guitar you use can scramble the cards, as we say in Italian
the thread is called "Direct Profiling - Who's selling their amps?" I"m about to order an amplifier for my kpa and this statement made me rethink the whole project. If 180 watt seem to be inefficient in some cases(as you explained) then i' m out of the game.I think that's the reason for the built in poweramp of kemper being 600 watt and not only due to it's ability to be used as bass amplifier.
Like Gianfranco pointed out, the perceived loudness depends on so many factors that I would come to the opposite conclusion: I'd definitely try to go the Camplifier or Ambrosi route. They are great amplifiers.
If I remember correctly I think the op in that thread said clean profiles are loud enough but distorted profiles are not which makes me think that it could be a settings issue like clean sense or distortion sense.
So I have turned the trim setting all the way up and now it's spot on for what I want. I can't say yet what it will be like through the 4x12 I use at practice but judging by how loud I can get it through my 1x10 at home I imagine it will be loud enough. The 1x10 is 16ohm with a celestion g10f-15 which from what I can find out is 95dB sensitivity rating.
I'm not saying you have to change the trim setting to get the power amp loud enough and I certainly understand why it's there and why it's set where it is but for my circumstances it works better for me on full.
I must point out as well there is no audible distortion with the settings I have.
Glad it worked for you Tom! 
And yes, 16 ohm and 95 dB... and a 10" cone... That cab is stubborn like a headstone! 
Yeah it's not the best design for efficiency lol but that's what I'm thinking if it can drive that cab well then the 8 ohms cab at practice should be no problem. Anyway I'll stop thinking out loud now lol.
Tom
How much louder did the Ambrosi get after maxing the trim pot?
Is there no danger in doing this...Gianfranco?
I suppose it's hard to say because of so many variables but for me in my setup I'd say it was roughly twice as loud for the same number on the master out volume with the same rig. One possible down side is you could be minimising headroom causing problems with transients.like I said in my situation I did not have any problems with with headroom and seemed to still have a wide dynamic range which was most evident on clean profiles.
No electrical or mechanical risks actually, just distortion
Of course be sure that the back of the unit is free and gets properly aired (in order to properly dissipating overheat).
16 dBu (the nominal Monitor output signal) equal 13,82 Vpp.
If the Profiler actually put out that voltage in normal conditions, the trimmer should be set at around 1/6 of its range. But that's an extreme value. When the trimmer is set halfway (which is the factory setting) it accepts up to 6 dBu before distorting, which Andrea estimates is a good and musical compromise between headroom and volume.
If you are able to measure the output voltage you might do some Maths by yourselves
HTH
A clip created with a Kemper Profiling Amplifier retrofitted with an Ambrosi ATM-68 power amp feeding a Dragoon 2x12" Celestion Century Neodymium mic'ed with a condenser Recording Tools MC-200 through an ART ProChannel preamp.
The Kemper Remote is used as well.
Thanks to Syrio Black and Salvatore Benintende (promoter of OpenMicRome) for their collaboration
Convincing clip. 
Convincing clip.
Convincing about what? Because if i didn't see the Kemper i would say that this sound was coming out from a floor multieffects unit like Line6 or something! Just my opinion!
@metalmike: Well, of course you're entitled to your opinion.
But talking about your floor multi-FX/Line 6 analogy: Nobody could tell a difference in a YT clip.
In saying the clip is convincing I'm meaning to say we have a good player here who shows how the Ambrosi can carry the room with clean and distorted guitar material. Is that better for you?
BTW: This mirrors my own experience with the unit as well.
@metalmike: Well, of course you're entitled to your opinion.
But talking about your floor multi-FX/Line 6 analogy: Nobody could tell a difference in a YT clip.
In saying the clip is convincing I'm meaning to say we have a good player here who shows how the Ambrosi can carry the room with clean and distorted guitar material. Is that better for you?
BTW: This mirrors my own experience with the unit as well.
First of all, to be clear, i was talking about distorted guitars! If i am not wrong, what we hear is a recording (with mic etc) not the room sound! So doesn't matter if it is a youtube clip! And i could tell differences between CLR and DXR in your youtube clip, even thought it was room sound! Also i didn't judged the quality of Ambrosi amp. But the sound that this clip has wouldn't make me buy the amp, not even Kemper, it is really bad for me and it doesn't sound like a Kemper! If it had a Zoom or a Digitech multieffects on the floor then everyone would make negative comments about sound, now that we see Kemper we must praise it for some reason! What's the reason? Because it is only Kemper? I don't understand it! I think sometimes we should speak the truth and leave back our fanboism (i am a fanboy too, i don't deny it, i love the profiler) or to please the others, if we want the profiler to become better and better! Look what Sinmix do and everyone blame him everytime he finds something that it's not working well! I thing the good criticism is more valuable than just telling that everything is great only because we are talking about Kemper! Don't take it personally, i have seen it happening a lot of times, we don't need to be like Fractal forums, if you know what i mean
You cannot argue with taste, period.
So I'm certainly not arguing how the player in the video chose to dial in his profiler.
And I'm not arguing with your taste and that it's not to your liking.
And you can never argue with my personal musical taste either.
Keep in mind though that what you say about the 'sound of the Kemper' is plainly wrong: It's not the sound of the Kemper, it's the sound of the profile you choose.
It's always been like that and you got it all wrong here, obviously.
I won't comment on your rantings about 'praising the Kemper' and 'fanboism' either because I find these comments inappropriate and quite embarassing here.
... wow... a bone of contention ... 
Display MoreYou cannot argue with taste, period.
So I'm certainly not arguing how the player in the video chose to dial in his profiler.
And I'm not arguing with your taste and that it's not to your liking.
And you can never argue with my personal musical taste either.
Keep in mind though that what you say about the 'sound of the Kemper' is plainly wrong: It's not the sound of the Kemper, it's the sound of the profile you choose.
It's always been like that and you got it all wrong here, obviously.
I won't comment on your rantings about 'praising the Kemper' and 'fanboism' either because I find these comments inappropriate and quite embarassing here.
No need to argue, we are expressing our thoughts here!
Let's don't play with the words, it's the sound coming out from Kemper, no need to make it more complex! It's the sound of the profile of the Kemper! Is that better for you? 
You were wrong thinking that we were listening room sound in the clip, it is recorded sound, and you didn't speak a word about it (afraid of admitting?)! But you have been convinced, though
The truth is never inappropriate and embarassing, some of you here you act like owning the company! Embarassing is also using the word "rantings" for me because i just said my opinion! Doesn't honor you at all!
Anyway back on thread, it's my birthday today so hopefully I might be back on to get my Ambrosi Amp. Just need to see how things play out this month (I do have two new guitars coming so don't want to upset the wife too much ). So here is crossing my fingers......
