I went to Tom Lee this evening and tried both 3900 and Z7. I found Z7 has the below advantages over 3900 (take into consideration of their price variation):
Z7 has a high sound destiny (sound thicker) with a deep sound stage. It is more in detail. 3D DSP is amazing with proper positioning. If we take a sphere as illustration, user is like sitting in the middle while all sound are pointing towards the "king seat". Z7 has a far more advance setting which u can adjust hz and khz of each channel (5-level adjustments to each curve) once you measure the room.
Z7 features a higher quality of video chipset, and its image wins 3900 by at least 20%. I saw a Epson projector in the showroom, not sure if it is a LCD. Image is very standing out and 3D.
I think the difference worth $4k, in fact it saves more than $4K since one does not always have to think about upgrade.
If without a power amp, which one is good? I only have a Onkyo 807. Tom Lee salesperson (I guess his name is Patrick) said Klipsch is the best match with Yamaha (even better than Mirage), but I am not sure if it is true
yes .. he wears glasses who is a little bit chubby and is a gentleman who is willing to explain and provide testing ... he gave me a A/B test between 3900 and Z7 with Kung Fu Panda.
a high sound destiny (sound thicker) is not depend on power amp. Power amp is power-up the signal from pre-amp. Pre-amp is very important. Of course, source is the most important.