Hello, Although a lot of information on this on the web, hoping fellow FM's can shed real light on the SQ / effect of a Down firing sub having a front-firing passive radiator for music.
My experience:
JBL SCS 140 8 inch sub.....Down firing and front ported......could give out 40hz lows.....if placed in corners....some more low frequencies achieved (2 yrs)
Bose 321 compact stereo 2.1 system...........down firing sub (internally) with front port......good 30hz bass........ (15 months)
Boston Acoustics Soundware XS 8 inch down firing ....bottom ported.....achieved 35hz and depending on placement....sounded more lower....(18 months)
Boston Acoustics ASW 650.....10 inch front firing sub with front port.......achieved 28hz and even lower....one of the best and smoothest subs I ever owned. (2 years)
BIC America H100ii....... Front firing and rear ported.......excellent sub for a 12 inch which went as low as 24/25hz........(18 months)
BIC America PL 200 (Series 1) Front Firing and rear ported.....awesome sub for 12 inch.....(I liked the H100ii more only upgraded for more sub power). (2 years and going strong)
Bottom line it is said that sealed subs with / without passive radiators work well for music....yes they do...to a certain extent......
Ported is best suited for movies.......I say yes....and also for music...provided placement and content is appropriate....
There are many who make subs out there ...lots of business and marketing.....it all ends on what pleases your ears and wallet.....
Audition is key and so are end user reviews........