Pros: Build Quality, Design, Sound
Cons: Not many accesories, No Bass Gain
REVIEW: Firestone Audio Fireye HDB
Full and long review here:
Part 1: Single Output
The HDB presents a warm and very rich signature. A full and very deep sound, which is very enjoyable and truly immersive. It's not what you'd call a flat and linear reference or analytical amp for sure (that's something for the Amp-S or JDS O2, for example), but rather smooth and engaging, giving higher priority to great dynamics with a noticeable added fun factor. Simply put, it's just 'Musical'.
The bass is probably the first thing to be noticed. In short, it's perfect. It's very full and deep with incredible extension and excellent rumble. It doesn't offer a heavy-bass low-end, and in fact it's missing the Bass gain option that the previous HD model had; not a bad thing per se, but would've been nice to have. Despite the slight extra coloration, the quality is great, very tight with good speed (although slower when compared to the Amp-S).
As for the quantity, well, it'd depend on the output. It won't make warmer/bassier phones sound as a bass monster, instead will give them better control, speed and decay. The HDB tends to have a better synergy when paired with more mid-centered to brighter phones, as it adds the low end they can be missing.
The midrange is very rich and well textured. Neither more forward nor recessed, but it's given an extra thickness and sweetness that makes it much more enjoyable. Vocals, as well, may remain in a neutral position in the whole presentation, but come out much more natural and articulated; very catching and with much deeper emotion. Still, the mids are not the most open and effortless, again when compared to more analytical and brighter Amp-S. Yet, the HDB has the upper hand in terms of texture and 'musicality'.
As expected from a smooth and warmer amp, the highs aren't the highlight of the show. They are very well extended, but to a lesser degree when compared to the lows extension. Quantity wise the treble is not lacking but definitely smoothed down; which is not necessarily a bad characteristic. In fact, the HDB does a great job to tame down some of the extra harshness that trebly/brighter sets may have. It works great with the SoundMagic full size HP200 (which sounded quite edgy and aggressive through the Amp-S), or the TWFK based IEMs like the R-50 and DN-1000.
While not being a detail oriented amplifier, the HDB detail retrieval is nothing short of impressive. Instead of being thrown to the front, they are presented in a more dynamic and natural way. The stage is more than big; it's huge, very wide with amazing depth. Not just that, the depth this FSA new product offers is without a doubt of the best I've heard. Dynamics are excellent and both instrument and vocal well separated. Imaging is pretty good; not the best yet, but everything sounds well-positioned for a warmish signature.