DFL's are oversized, "Idiot Proof", and loud! The quietest moderator is always going to be the ones sized correctly and tightly for the ammo it's shooting and has the most volume. The "Quietest Moderator" I have ever used in 5 years of shooting PCP airguns is the Huggett Astille. Most people don't like them because they look like a Dildo (Conical "Nose Cone" shape). If you don't care what it looks like and are concerned solely with a quiet moderator it's definitely worth checking out. The Huggett Atom, Belitta, and Snipe are also very good moderators. For reference, I have used Huggets (my favorite), DFL's, FX Empty cans, STO Sarissa and Faulx, 0db (very close to Huggett, same construction but slightly oversized), Impulse Air 1350, and an overbarrel Fox 600 series.