Dali Helicon 400 or Acoustic Zen Adagio?

I have owned the 400 and the 800mk2, with different amps, and heard them with many other amps. I disagree that they are amp sensitive. The sound good on an average amp, but will reveal the flaws to some extent, and they are superb with a great amp. I have also read comments from others that confirm dali's arent as amp fussy as other speakers. I would suggest above 100w will drive and control them very nicely in moderate room.
Tremendous speakers - i tried many, many, brands...

Dave,
Your Conrad Johnson will definitely have enough power!
I'm driving the Helicon 800s with 180w, and I think it is more than adequate. The lowest power I heard them driven with was an Ayre 70w and I would say that was not enough, so the answer for the minimum must be somewhere above that. More will always be better. Perhaps over 150w?
I do think that once you have enough power, the Dali's arent that amp fussy from my experience, and also from what I have read.
I had an experience with a 100w Primare on Dynaudio speakers, and we just could not get them to sing.

As an example, I know how these speakers sound driven with 180w of NAD M3 power and sound excellent (as a budget solution), but the base was not absolutely controlled. Very powerful base, though. Also know how they sound with a 180w Gamut amp, and the base is superbly controlled. same power...

Dcstep, I actually found deep harmonic base to be one area that attracted me to the Helicons in the first place. In some respects, the mk1 was slightly better, but there were other compromises that I wouldnt go back to.
I use a few tracks for testing the extreme low bass including Bela Fleck's 'flight of the cosmic hippo'. Or try Sarah McClaughlin's 'i love you' (i think that is the track). Of course some orchestral pieces, and some Patricia Barber is good for this. Not sure what the frequencies are but they are low!
In my experience with quality amplification (especially high end solid state), the Dali's were superior to some of the others speakers in a similar price range. I tried Revel, B&W, Focal, and others.
I find the base a little thick and lacking in harmonics when they are too close to the rear wall, but as soon as you move them away, they come alive. Perhaps you should try this? Maybe it is just the combination of my system and room, and good cables with a tight bottom end also makes a difference. With some extreme high end cables, I got worse results in the base harmonics.

Dcstep, it sounds very much like this speaker doesnt suit your needs and equipment after 5 amps! I must admit I havent seen this issue in my experience with them, but after 5 amps, is it time to switch to a different speaker?

Sounds like you have a wonderful set up and great speakers. I havent heard the Baby Grands myself.
I listened tonight to some of my test classical tracks eg Prokofiev's Romeo and Juliet and Schubert's 9th, and specifically listened to the deep base harmonics/tonality, and I am still impressed. Must be my set up and room etc. The speakers I listened to before buying the Helicons included Thiel, Revel, Triangle, Dynaudio, Focal, B&W, Elac, Sonus Faber...that i can remember. I also listened to some extreme high end speakers. It took me ages. It is so hard to find what works well for your taste, your equipment, your room, and last (and definitely least), your budget. I am extremely fussy.
Sounds like you are too :-) so if yours are doing it for you already, why change? You are winning! I rare thing in this game in my books.

Dcstep and Steidlguitars,
We will probably be more aligned after this post. I re-read the thread and realise that there may be some miscommunication, and I have to apologise.
I owned the Helicon 400 for about 18 months, and upgraded to the 800 mk2, so all my comments regarding recent testing of the deep base are with respect to the 800 mk2 which I own currently.
I would say this - the 400 is a superb speaker which I would recommend to anyone in a heartbeat. It comes extremely close to being a full range speaker, and I would say it is one of the best in it's class. Perhaps there are some compromises in the deepest base notes. I dont recall this ever being an issue, and I cant go back to test again. So I have to accept Dcstep's comments, and maybe it is asking too much of the speaker.
The 800 mk2 is even better and is most definitely a full range speaker. The deep base is outstanding. There is a reason why they produce an 800 and dont just stop the range at the 400, but of course, they cost more :-)
Sorry for the confusion.