Ok, I have a conventional radio in my 4/4 and two good JBL speakers in the footwell. But I have often thought about it in the same way that your solution is very smart and fantastic. BTW I think the sound is more natural in the interior than through speakers radiating against the knees. I have hifi at home, in the car I want a natural sound with appreciation of the mids in the first place. Just like in the old days. In our 1968 Mercedes 230 Sedan there is a single speaker in the dashboard that sounds completely satisfying and similar to yours. Sometimes less is more.
