This year, we’ve reviewed samples from most of Fiio’s broad product offering — DACs, amplifiers, and dedicated audio players. The company has almost always had a small selection of in-ear monitors on offer as well, but those IEMs have never been what Fiio is really known for. That’s about to change; Fiio has introduced a new line of IEMs — the F series — that show Fiio’s commitment to becoming a real competitor in this space. Today we’re looking at the top-of-the-line F9 Pro, a triple-driver hybrid IEM.
The Fiio F9 Pro is technically dense for an IEM in its price range. Inside its aluminum housing are three discrete drivers — a 9.2mm dynamic for bass frequencies and two balanced armature drivers for midrange and treble. All IEMs in Fiio’s F series feature this hybrid triple-driver configuration, but what sets the F9 Pro apart is the inclusion of Knowles balanced armature drivers; Knowles is the best-known manufacturer of BA drivers, and their products are often found in far more expensive headphones. The F9 Pro’s Frequency response, according to Fiio, is in the “Hi-Res Audio” range of 15 Hz to 40 kHz.
The F9 Pro has an impedance of 28 ohms and a relatively high sensitivity of 106 dB/mW, making it easy to drive out of any device we used for testing, but surprisingly it did not hiss when used with our most powerful headphone amplifier. The detachable MMCX connectors are a nice touch, especially for those who want to experiment with balanced sound (see: Fiio’s X3 MkIII DAP), though in testing ours did work themselves loose on occasion, causing sound to cut out until we fixed the connection. The F9 Pro are available in just one color — matte titanium gray — which looks great on its wavy aluminum housing.
The F9 Pro sets a new bar for bundled accessories. In the box are two storage cases — one soft pouch and one pelican-style hard case. The hard case is great, but it’s clearly bigger than it needs to be for just the IEMs; a little bigger, and it could have held one of Fiio’s smaller DAPs as well. Two MMCX-terminated cables with integrated over-ear guides are included, one balanced (silver-plated copper, 2.5mm TRRS), and one single-ended (OFC copper, 3.5mm TRRS with mic & controls).
Both cables are thin and not at all tangle-proof, but they do their job.
Finally, for included ear tips, we have a new record — four different styles of tips are included, in three sizes each. These vary in shape and material, and each provides a slightly different sound signature; after some experimentation, we seemed to get the best mix of comfort, isolation, and bass response out of the clear spherical-shaped tips. It seems like we’re seeing more and more included fit options with IEMs; it seems like an arms race, and we can’t help but wonder where it can go from here. In any case, you’re essentially guaranteed a good fit with the F9 Pro.
We were very impressed with the F9 Pro’s sound. Its large dynamic drivers produce punchy, controlled, clear, bass with very deep extension; the F9 Pro is one of those headphones that provides impressive bass without sacrificing the rest of the frequency range. As is to be expected from high-quality BA drivers, detail retrieval is also generally excellent through the mids and treble.
