Benchmark is UP2 which allow effortless fine-tuning of the volume with the wheel.

Sounds good. The iPhone only has 16 (click) steps, which makes it difficult to fine tune the volume with the UA2.

Shanling - want to chime in here?

How do the volume controls work? Is it with a click or a press and hold? If there are steps, are they adjustable? Does the UA3 allow the fine control of volume that the devices with a wheel offer?

The UP2 is a fantastic device for what it is, but with the advent of lossless streaming, the ability to connect such a device to the phone over the USB DAC becomes that much more desirable. The devices on the market that already possess this ability have now become much more attractive.

But you also never explicitly advertised that it wasn't. I think this is a reasonable expectation considering that your products are designed to be used portably with iOS devices and are advertised as "Hi-Res". In effect, with the apparent exception of the UA2, your devices are not capable of...

This is a serious limitation which is not clearly indicated in the advertising. Has this been rectified in the UP5?

I want to play lossless through the usb dac in the UP2

The UP2 appears to not work with the Fiio LT-LT1 cable. The iPhone sees the UP2 as a device to be charged and posts a notification that it draws too much power. Any chance of getting this fixed with a firmware update?

Anybody get this combination to work? With the iPhone SE, I get an error message that says the UP2 requires too much power.

No SPDIF Input

You could also plug the PS3 directly into the HDP if that's the only analog source you're going to be using with headphones.     You will be using both preamps when you output the analog signal of the HDP into an analog amp input - your amp has no main-in. Setting the gain control to about...

Low impedance headphones require current to see more power.  High impedance headphones require voltage to see more power.  Portable amplifiers will typically have little or no effect on low impedance headphones as they are designed to limit current output to extend battery life.  Portable...

The stock steel cable is very microphonic.  The HD-600 and H-650 cables are much better.  I didn't hear much if any difference between them with the HD-25 - the HD-600 cable has a 3.5mm plug and the HD-650 cable a 6.3mm plug depending on your needs.  

Quote: The HD 25-1 II is a very sensitive headphone that can be driven to loud volume levels from a DAP.  My experience demonstrates that amping makes the HD 25-1 II clearer and crisper at the same volume level.  YMMV.