I purchased my Apogee Duetta Signature ribbon speakers in 1991, and have spent the last 19 years building around them. They provide magical transparency, soundstaging, and musicality. I have paired two matching Paradigm Reference Servo 15 subwoofers with the Duettas. The Duettas are powered by a pair of Bel Canto Reference 1000 Monoblock amps. I use the X-30 crossovers which come with the Paradigm's to make the subs work with the Duettas.
I’ve got a pair of Signature Series IIs (original owner) running with a BAT VK-600 w/ BAT pack, BAT VK-5i tube preamp. I can’t imagine why a subwoofer would be needed. The bass tightness that goes down into the inaudible range where you just feel it is astounding with these speakers. Hit any big challenges when separating out to a sub?
Nice system... There's nothing like the 3D you-are-there of full range Apogee ribbons... I also have D. Sigs and after 30+ years of enjoying this hobby I have found them to be the most rewarding speaker I've ever owned. Let me ask you: How far are they from the front and side walls? How about from each other? Room size? Do you use a separate crossover to split the signal to your subs first in order to "lessen the work" of the ribbon woofers? Perhaps the X-30 at 50 or 80 hz? Just curious... I'm sure we could have lengthy conversations. Once again... nice system.. Best regards PS: my virtual system hasn't been updated on this site with any new pics, it's still showing my previous Mini Grands, but I'll be correcting it soon.