The PHA-1A is a headphone amp~DAC which like other Sony kit is somewhat pricey. The list of things against it well outnumbers the list of things in its favour.
Let’s look at the cons. It’s really only designed for Sony or Apple gear, but can be connected to a laptop or even an Android device with OTG capabilities (which was probably never the intention, but it works that way with my Huawei Honour 9). It can only be connected to Walkmans that can play at least CD-quality music. My older Walkmans cannot be connected to the device, but my iPod Nanos have no issues. The battery life is not just pathetically brief (about six hours at most), but the battery cannot be recharged while the device is switched on. Huh? How dumb are some people? (I add as aside that the more expensive amp~DACs in the same Sony range suffer from the same drawback.) There are no line-in or line-out ports apart from the usual 3.5mm socket for a pair of headphones.
After that, are there any pluses? It sounds nice enough, but it’s premium price doesn’t result in premium sound. Knock £50+ off the price, make it more versatile (i.e., line-in and line-out ports), make it something that can be recharged and used simultaneously, and you might have a deal.
Overall, I can’t recommend this.