Having a roll-off in the room-sound above 4kHz is very much consistent with concert hall sound (cf. regonaudio.com/Records%20and%20Reality.html). But without a little of the AirLayer in action, this roll-off seems to me to start too far down in frequency—in the rooms I tried at least. The AirLayer option will fix this up. And the result is then something truly akin to concert hall sound, as I mentioned also in my earlier review of the JansZen zA2.1.
While the bass performance of the larger model is naturally somewhat superior—though this zA1.1 stand-mount has more bass than you might expect—this stand-mount model allows you to raise the speaker so that the mid/tweeter is at ear height. To me at least, this is important. The floorstanding model is tilted to position the ear correctly relative to the mid/tweeter axis, but, as with so many floorstanders, one is looking down a little at the music. The present stand-mount can also be mounted to make the music level with the listener, and the result is a kind of magical expansiveness—things like the Grieg sonata recording mentioned above can seem not only tonally convincing and transparent, but also spatially much like what one would hear if one were sitting and listening to the performers. This is one of those “must hear it to believe it” experiences that floorstanders seldom offer in this particular way.
These speakers will play loudly, for small speakers, but small they are, and they are also not high in sensitivity—nominally 85dB. At the same time, they are, according to the manual, not to be driven by an amplifier with more than 400 watts per channel. (An ultra-high-power amplifier can damage them.) Now the amplifier I was using, the Benchmark AHB2, is rated at 100 watts into 8 ohms, 190 into 4 ohms, and thus seems of appropriate capacity. (I was afraid to trot out the big Bryston and while I did try the Sanders Magtech, to admirable effect, I was feeling a bit nervous about doing so.) The Benchmark was clipping at loud moments in the Mahler—which I was not playing that loudly overall. In effect, there seems to be a window of opportunity here—I think something like 200 watts into 8 ohms would be ideal. The speakers are supposed to be undamaged by small amounts of clipping, incidentally. For a gigantic room, there is the floorstanding model zA2.1 and, recently, a fully active, bi-amplified version of this, which has large dynamic capacity and truly deep bass extension.
I should also mention that the model under review, like the floorstanders, offers phase-linear behavior, with a first-order crossover from the front woofer to the electrostatic unit at 500Hz. The blending of the drive units is excellent, and the electrostat covers the entire range of maximum hearing sensitivity. How much the phase linearity as such matters is, as always, a bit controversial, but in practice things such as the attacks of piano notes sound more correct than usual.
The zA1.1s have adjustable treble level—I turned it down a good bit in my room. (This is in addition to the AirLayer adjustment.) They also have a switch to introduce a notch in the bass if one wants to put the speaker against a wall. This seems to work well, though the speaker really gives of its best in imaging in free-space mounting on fairly high stands to get the treble unit at ear height. Incidentally, you can experiment with turning up the treble a little above the level that would seem natural if the speakers were aimed at you and then angling the speakers slightly away from you for various possibilities on total radiation into the room versus direct arrival.
Some people expressed concern about my earlier review of the floorstanding JansZen model, the zA2.1, because I emphasized the adjustments to an extent that made them nervous about getting the sound correct. Don’t worry! It is quite easy to dial the sound in, and the adjustments are really useful.
With most speakers, you are stuck with what the designer did, averaging in his own mind the possible types of rooms and positions. You cannot make things any better except by moving the speakers, treating the room, or using external eq or room correction. You are just stuck. With the JansZens, you have additional flexibility, and you ought to be grateful. Not all rooms are alike. In particular, the ideal AirLayer setting will be different in different rooms—but you will know easily when you have it right.