My personal experience with attempting to add subs goes way back: Sunfire 10s then 12s, much later and still unplugged SVS Ultra and Plus (the ones that look like tall barrels). These I tried when I had Magnepan 3.5Rs (hope those 3.7s mentioned earlier are significantly better, but I have my doubts). I tried using an active XO but the cheap ones kept blowing up. Looks like OCD Hifi Guy is having Marchand make a new version which would be worth checking out.
I replaced the 3.5Rs with a pair of Emerald Physics KCIIs with 2 significant factory upgrades: they came with a BOM which essentially blends subs into the main speakers. Again no bueno (not good). The KCIIs blew away all my attempts to marry 3.5Rs and subs. They are capable of really good bass on their own, with an incredible 3D soundstage AND are super efficient, BUT, my room is 19 x 35 x 12 with lots of glass on front and back walls, plus open up/down stairwells. My point is: why not let the speakers make the bass instead of the extra cost of a sub, interconnect, power cord, and struggling to find the best placement in your room. Most likely, that requires 2 subs
The really good news is EP is blowing out their remaining inventory as they are moving assembly from Texas to CA, I think. The 4.4s (I think) with 15" driver (I saw an adv on Agon) would bring you a lot more quality bass MSRP $6000, BUT, you can own them for $1600.
https://www.usaudiomart.com/details/649617064-emerald-physics-44-moving-sale-brand-new/
OR
3.4s $5K/$995!K,
https://www.usaudiomart.com/details/649616505-brand-new-emerald-physics-34-direct-from-the-factory-m...
hth
I replaced the 3.5Rs with a pair of Emerald Physics KCIIs with 2 significant factory upgrades: they came with a BOM which essentially blends subs into the main speakers. Again no bueno (not good). The KCIIs blew away all my attempts to marry 3.5Rs and subs. They are capable of really good bass on their own, with an incredible 3D soundstage AND are super efficient, BUT, my room is 19 x 35 x 12 with lots of glass on front and back walls, plus open up/down stairwells. My point is: why not let the speakers make the bass instead of the extra cost of a sub, interconnect, power cord, and struggling to find the best placement in your room. Most likely, that requires 2 subs
The really good news is EP is blowing out their remaining inventory as they are moving assembly from Texas to CA, I think. The 4.4s (I think) with 15" driver (I saw an adv on Agon) would bring you a lot more quality bass MSRP $6000, BUT, you can own them for $1600.
https://www.usaudiomart.com/details/649617064-emerald-physics-44-moving-sale-brand-new/
OR
3.4s $5K/$995!K,
https://www.usaudiomart.com/details/649616505-brand-new-emerald-physics-34-direct-from-the-factory-m...
hth