Pioneer XDP-300R $1199
This is the prince of this crew when it comes to price. And to size. The Pioneer XDP-300R is a large, angular player, heavy and with a large screen. On the left side is an actual rotating volume knob (with 160 levels). On the right are play/ pause, skip and power buttons, along with two slots for micro SD cards. Cards up to 200GB each are supported, so you can certainly fit plenty of music in there. In addition, you can use up to around 25GB of the 32GB of storage in the device.
This is an Android device with a fairly standard implementation of the OS (it uses Marshmallow). You can use the device for all kinds of things beyond playing music, since you can download your choice from tens of thousands of apps in the Google Play store. There is no camera, though.
The Wi-Fi supports up to 802.11ac and the Bluetooth supports the apt X codec, but not AAC, as you might expect with an Android device. Owners should choose their Bluetooth headphones carefully.
The unit will play just about all the main music formats. It handles Direct Stream Digital all the way to 11.2MHz sampling (quad DSD). It can do PCM-based formats up to 384kHz sampling. If you have many of such files, those two micro SD card slots are going to come in handy!
The unit doesn’t have a line output as such, but it does have a setting called “Fixed Line Out Mode” which sets the volume to maximum and renders the volume control ineffective. This is accessible through settings or through the front page of the player app. Also there is a button for ‘Stand-alone Mode’, which switches off the Wi-Fi, Bluetooth and screen to reduce possible interference. And it supports balanced headphones using a dedicated 2.5mm socket. I was a bit surprised when measuring the output to find that it maxed out at precisely 1V RMS. I hadn’t noticed that in use, because there was always plenty of volume regardless of the headphones used. But that did seem low. Particularly in fixed output mode into a high impedance input, having a higher output voltage would be nice. In the settings there’s a gain setting and it was set to ‘Normal’. There were a couple of lower settings, plus one marked ‘High’. I selected that, and the output went straight to 2V RMS. That’s what I used for my testing (with the usual proviso of keeping the level below clipping at all times).
It happily delivered an output that will lift high impedance headphones to 11dB above their sensitivity specification, and low impedance ones to 17dB above.