Fostex is a huge pro-audio-based company out of Japan, but it also has a domestic arm, and that domestic arm makes some very clever products. The HP-P1 is the perfect example of just how smart Fostex is at reading the market.
The HP-P1 is a DAC+headphone amplifier, but one designed for those on the move as well as those with a penchant for plugging in next to a laptop. It works by using a built-in battery, so that you can hook your iDevice or other smartphone to the USB connector. It has apple Authentication (it registers on the ‘About’ section of your iPod or iPhone) and a shortened Apple connector-USB cable so that the two can hook up on the move. It also has a separate traditional USB connector allowing the user to charge the battery from a laptop or a plugtop USB charger. You cannot charge the P1 through the iDevice (that’s a no-no under Apple’s own rules). The P1 comes with a dinky little pouch, but should also come with a strap or two to harness it to your smartphone, or iPod (at a pinch, two of those red rubber bands posties leave all over the place, or a charity wristband both make good alternatives). It features a conventional potentiometer combined volume control/power switch that feels good in the hand, and has three gain settings and two filter settings to fine tune the sound. It’ll take you about five hours from exhausted to full battery and the fully-charged battery will keep you going from London to New York, or roughly seven hours.
Under the hood, it’s built using the AKM 4480, 32-bit DAC chipset, which is used almost exclusively by Fostex for this device. It has two filter options; the first is a standard sharp roll-off, but filter two is a minimum delay filter to limit pre-echo (this only works on the digital input, naturally; the analogue mini-jack line input is untouched by a digital filter option). I significantly preferred option two in use, but the beauty is the option is there for all and instantly switchable. There’s also a cheeky bonus that comes with the Fostex. It includes a line audio output mini-jack, which allows you to take the output of your iPod and hook it to a full-blown stereo system or even to a recorder, without the need for a docking device. It also comes with a Toslink connector for digital hook-ups…and potentially digital recording off an iPod!
Fostex recommends headphones of a greater than 16-ohm impedance and the amp itself delivers 80mW, more than enough to drive most headphones and IEMs well. Don’t move too far outside of its happy place though, because the amp will begin to show its limits. So, no power hungry planar magnetics type headphones (the HiFiMAN HE-500s were a stretch). On the other hand, a pair of headphones like the Sennheiser HD-25-I IIs, the Focal Spirit Ones or the Sony MDR-7506s I use for recording work perfectly.
There’s three questions to address here. The first is ‘why?’ The iPod has a perfectly good headphone socket in its own right. This is a pretty simple fix; the HP-P1 brings desktop audio quality to portable audio rigs. It allows the iPod user a wider range of headphones at a wider range of volume levels without strain, and – unlike any iPod or iPhone bought in the EU – there isn’t a volume limit to constrain you. While that means ‘louder’ which spells hearing damage, it also means ‘more dynamic headroom’ at any volume level, which means better sound. Unequivocally. Uncontestably.
The next question is ‘how does it compare?’ In a way, this is a tougher question because it’s almost in a class of its own. Few single box devices for a portable player combine digital input and amp in a single, elegant box. There are single-box headphone amps that are designed to glom onto a computer for someone wanting better quality than the supplied socket. There are stack box systems comprising little DAC and little headphone amp that when all strapped together turn a svelte little device like an iPod into something that makes you think “prototype”. The Fostex takes all those things and turns them into one box that is still inherently portable.
The last question is ‘how does it sound’? It’s crisp, clean, inherently neutral and detailed. Extremely detailed. This isn’t the kind of headphone amp you’ll choose if the first word that comes to mind is ‘rich’ or ‘lush’ or something similar. Instead, it’s rather like choosing really good detailed solid state amplification in your main audio rig. It’s precise and controlled, and pretty much what you need from a headphone amp on the move. And it’s in the sound quality where the iPod on its own falls flat, lacking dynamic range and energy on any recording that has some dynamic range. In short, it’s like you moved your hi-fi system in between your ears.