I bought a "Single 40" cabinet recently. I don't think it "assists the sound quality" in any way. A couple of things to mention about this cabinet. The perforated side panels are not a tight fit in the channels, and rattled if I tapped on the cabinet. I disassembled everything and used some thick rubber electrical tape to create a tighter fit. I also used "Blu Tack" to islotate the shelves from the brackets. With these things done, I'm happy with the cabinet. Sonically, there are certainly better choices, but they are much more expensive.
JD
JD