Nearfield Acoustics Pipedreams

Has anyone heard these before?
What are the problems with a line array?
Any problems with the crossover?
What kind of amplification to use?
Are the subs powered or passive?

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What kind of amplification to use'
Pick the 'flavor' of sound that you prefer, (I won't go there). These are very revealing speakers, so the core sound that you pick will be what you hear.
The towers are VERY efficient, as I recall, mid ninties.
Once I used a Gryphon Callisto on the towers and various others on the bass units...the Gryphon bested, Ayre, Mac, Krell, conrad johnson, and it wasn't really close musically. That made me a lifetime Gryphon fan (well, that and the L1 Preamp from back in 1990--another story).

From the second or third post
I have heard them with tubes (a Melos amplifier that didn't blow up) and they sounded great.  Had I owned them I would have used Lamm ML 1.1s, and I'm sure they would have worked, I don't think they were that tough a load to drive at all.  I'm also certain that lrsky's advice from prior posts (as quoted above) is spot on.
You need a large ss amp like Pass 350.8 and active crossover active subs.Sound ok.
I'm trying to set up a pair of pipedreams with their subwoofers, but I can find no documentation online about them, so finding an adequate amp for them is very hard.
IIRC, the subs are built to be operating below their resonance, so the crossover is EQ'd to give a boost of 6dB/octave. So you need a **lot** of power- a Carver 1000 watt amp (as the sub amp) I heard with them was clearly straining.

If it were me I'd go with a different sub.