I've been doing exactly what you're talking about for close to 20 years on the same sets of speakers. I bypassed the onboard XO, used a DCX2496/NU12,000,
set the XO points I wanted and never looked back. The NU12,000 are directly coupled with # 10 and there is perfect cone control with ZERO problems. It's
very comparable to servo control subs I've been using for close to 50 years. Infinities bass columns (50 years) Rythmic plates with GR's servo drivers (10 plus years)
I can use ANY sub-driver with the combination as long as I remove the passive. I've never run into problems and I've done 100s of sub drivers, MANY were
onboard towers with a bi-amp option. I've also swapped out sub-drivers, did a little work on the cabinet size along with adding dampening material to the existing
cabinet with great results.
I used to ADD Infinity servo circuits to speakers like the RSQL series and was actually contracted by Infinity to make close to 50 or so conversions. It was very popular
with the 12" DVC (smaller secondary coil). As good as the Infinity was it had problems in relation to speed. I'm a serious small planar/ribbon user.
Direct coupled, adequate wire size, and just about any power amp will work. I doubt you could find a better sub/bass system. If I can't break it it's pretty darn tough.
I recently purchased a mini HT 8 for a FR system to compare. NU12000 for subs, 4 15" GSR subs, NU12,000 for Bass columns using Dayton RS225A 8" bass woofers in columns (6 per side), Cary V12Rs/EL34s driving GSR Neo 10, 6 per column and Son of Ampzilla II driving 10 GSR 3.0 ribbons per side in columns. ALL direct coupled
All the cones are wired at 8ohms, subs, and bass columns. The Neo 10s and 3.0 ribbons are wired at 12-16 ohms.
I like EL34 mids and lower HF 300hz to 6000hz, BUT I've lost a considerable amount of HF in my ears and I wanted close to ZERO feed back for the HF 6000hz >
They don't build what I NEED for MY ears, so I embarked on my final personal speaker system.
I'm honestly not interested in how it measures as long as I can HEAR what I want and be able to adjust to my personal needs. I'm pretty sure after I do a little
tinkering and then MEASURE the result it will look much like a hill climb from the bottom to the top, BUT I will be able to hear what I want to hear and not
have to adjust hearing aids to compensate for hearing loss.
It's one of those cases that in 5 minutes I could change it back for the younger ears that frequent my shop/listening rooms. Many of them are DEAF
from BOOM BOOM anyway. They have a LOT of LF loss, behind improper protection at work and their car stereos.
I wanted to build a low-dollar system that could rival what I have been seeing/hearing at shows for 40 - 300K. I'm close to 5K, less the preamp and source.
I need to weld up some clamp/stands for the planar/ribbon columns and get them powder-coated. I just found a new local guy. We'll see.
It may not be the pinacol of modern-day aesthetics, but then it doesn't cost what a pretty nice house could cost either AND it can be changed fairly easy
when I kick the bucket for the next guy/gal, IF they want. Early spring I should be finished. It's too cold to work in the shop this winter.
Regards