I've heard great things about this one, including the phono option. Is it also a good match for power amps from other brands, like ARC (I have the GS150) or will this one only make sense with a darTZeel amp?
I haven't heard the new 18NS yet, but I'm quite familiar with the previous, original version. It's fairly easy to match to a number of different amps, as you can use RCA (100 ohms output impedance) and XLR (600 ohms).
Looking at the specs of the GS150, it has a fairly high input impedance (300K!), but if you consider that AR's own pre of the same line (GSpre) has similar impedance specs (500 ohms balanced, 250 ohms SE), seems like the amp should handle it well.