Best preamp is no preamp: always true?

Dave, that's what I thought. As usuall it carried a good thought as well.

Add to the list of integrated amps with a passive input the Ayre AX-7e.

I have not heard any of these (passive input) integrateds. I would like to, though. Their power amp sections were designed specifically to be run with a passive pre' section (I presume) and so would most likely do just fine---more than fine---in this configuration, especially with a high output, low impedance CDP or DAC.

Could these integrateds be tested with and w/o an active pre-amp by turning the volume all the way up on the Int amp and use it with an active pre'? And then take the pre' out and use the volume control on the int amp as usual? Has anybody tried this with such an integrated amp?

Does the Berning 270 amp have a passive input section?

Yes I have. I've tried this with my passive integrated. It sounds much better when you have the active gain stage involved.Without it the sound is clear and precise but a tad thin without the help from a tube linestage. After trying it both ways I couldn't see going without the active linestage/ gain-stage in the loop. I liked the sound so much I'm getting a unit built without the volume control that is nothing more than a low gain active stage to go between my DAC and Integrated.

Solman989,
In case of integrated amps you ought to figure that the amplification part does it all where the volume pot usually connected onto the driving stage(realy becomes active after all)

In some of the passive-stage integrated amps you may feel the lack of drive and controll f.ex. Creek 4330. At the same time I could contradict myself saying that it just hasn't enough watts, but after trying it to work as poweramp only with active drive it was way different:
Still lack of power but controll increased no doubt.

Another of my discoveries would state that you can add even a chain of preamps and you will gain even more and more controll but to the point where's your music would become overcompressed since every preamp would invert signal i.e. make a negative feedback level deeper.

Counterpoint power amplifiers have option to have a high impedance/sensitivity driving stage specially designed for the passive preamps. This driving stage isn't recommended for the best product performance to whoever prefers active preamplification... Which means that preamplification and driving stages should be just enough not to get high level of a signal compression and so I guess that hobbyist who's matching components should pay to some degree an attention to this factor such as a number of preamplification and driving stages of mainly separate amplification components.

For what it's worth, I've found my Levinson 390S running directly into my CAT JL-3's to sound much better without my ARC Ref 2 Mk II. Of course, the 390S DOES have the same analog volume control found in Levinson preamps.