Ouch.
If I understand your wording, you
are the "wife factor," correct? Your husband wants the nice big sub, and you want a forty-pound flower pot in approximately the same space. Have you considered asking him to build a shell to go around the sub?
If he primarily encloses the rear two-thirds and leaves ~four inches clear on the sides and top it shouldn't have any undesirable effect on the audio, and if well done the acoustic chamber might even produce an attractive coloration. Taper the shell itself (smaller toward the rear and larger toward the front opening) and find a veneer to match the S-10's grain and it won't noticeably detract from the beauty of the S-10, either.
Advantages: You'll have a safe place for the flower pot, he'll have the convenience of being able to adjust his components without having to disturb the flora, and you'll both sleep better knowing the geraniums haven't piddled on a $500 subwoofer.
Disadvantages: Some work involved, and he will have to adjust his conception of the room. Rather than seeing his beautiful sub from all angles, he'll have to be content with a front view and an additional bit of furniture.
Is this an ideal situation? No.
Is it a compromise I could live with, as a husband, a music lover and a competent woodworker? Absolutely.
- M.