Bookshelf Speakers Sitting On Dual Subs?

Coin sitting on edge sitting on top of Elac Adante 3070.

https://www.youtube.com/watch?v=AtKKFe7sku0

@normb  👍

Stereophile:

While the 8c is big for a stand-mounted speaker, its cabinet isn’t big enough to develop a lot of bass; Hofmann’s Iron Law has not been repealed ... D&D takes advantage of placing the speakers close to the front wall with what they call Boundary Coupled Bass. When the 8c is positioned from 4" to 20" from the wall, the direct output of the rear drivers is acoustically coupled to the energy reflected by the wall such that they act as a single source ...

So it seems desirable to place D&D close to the front wall. Now the issue you have to cope with is whether which location is optimal for Elac sub. if you want to stack them up ...

What is the end goal you are trying to achieve? Louder over all playback levels, more thump? The 8C’s appear to have a sub out, is it full range or do they have low and high pass filter capabilities? The drivers in the 3070’s appear to be on angled baffles, are you using them in a side firing configuration or a front and back configuration? Are the 3070’s currently in the room now and if yes are you having any issues?

The first potential issue that jumps out to me could be a phase issue. A lot of drivers facing different directions, specially if the 8C’s are run full range. Potentially a lot of different paths for the sound waves from different sources to take on their journey to your listening position could make for some muddy bass.

The another possible issue if the 8C’s are full range is that your subs may not have much to do. According to the 8C’s spec’s they are good down to 30 Hz, not much in recorded music gets that low, not too mention lower.