I had some Axiom M22TI bookshelf speakers I used in this manner and didn’t feel it was a negative. The dual subs help cancel standing waves, and as long as the tweeter height is satisfactory let your ears be the judge. I had used some Audioengine stands for my setup as they provided some tilt. I am running dual subs for my current setup but they live behind the primary speakers now, not under.
Bookshelf Speakers Sitting On Dual Subs?
I have a couple excellent subs - Elac Adante 3070 - which have pretty effective DSP. I'm thinking of buying the Dutch&Dutch 8c (also DSP). The Elacs are rock solid. I'm thinking about placing the 8c on IsoAcoustic stands on top of the Elacs so the 8c is even with the front of the Elacs and separated by the Iso stands: running the DSP for the subs and then the 8c. Any real drawbacks to this set-up?