twoleftears-
The one advantage the JBL had was size. The L25 is a lot smaller and lighter. That too is a design consideration. But as long as all we care about is sound quality, transmission line all day long.
Transmission line is best when properly implemented.Inclined to agree. First speakers I built were transmission lines using the 1980 Speaker Builder Design of Roger Sanders. For drivers I used the 10" woofers from my JBL L25. The bass was obviously, considerably, impressively better than when the same driver was in the ported JBL. More efficient, smoother, deeper. Not even close.
The one advantage the JBL had was size. The L25 is a lot smaller and lighter. That too is a design consideration. But as long as all we care about is sound quality, transmission line all day long.