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.

Quote:   Do it now, the money will come later.  [Henry Miller]

I finally got a chance to get to the Apple Store and demo the Amperiors and I was not impressed.  As a long time HD 25-1 II owner, I thought perhaps the lower impedance of the Amperior would offer ampless the sound of the HD 25-1 II with an amp, which I believe is Sennheiser's intention, thus...

Quote:   At full gain the RCA output is 2.6Vrms.  Fixed outputs are typically 2.0Vrms so try setting the gain at about 75%.  The goal is to set the gain as high as possible without hearing any noise from the preamp.

With most cables you have to use a mini-adapter on one or both ends.  Van den Hul makes the Optocoupler Mk II in a mini to mini version.   http://www.vandenhul.com/p_B42.aspx   Quote:  

The HDP has an RCA Coaxial Input so a 75 Ohm RCA-RCA cable would be appropriate.  If you have some reason to prefer the BNC output, you could always use a hybrid cable or adapter to connect to the HDP.  Also this from the manual:   Quote:   Quote:  

If you have high resolution files, then it would be useful to incorporate a hiface into your system so that you can play them back without downsampling. The HDP is capable of converting up to 192kHz digital files to analog.  As to the benefits of upsampling, you will have to listen for yourself...

The HDP always functions as a preamp unless headphones are connected.  If your computer is properly set up, you should be able to output "bit perfect" data to the HDP.   Quote:  

I'm running optical from my MacBook Pro and can output up to 96kHz including 88.2kHz.  With USB, 88.2kHz does not work. This is not a function of the DAC but of the S/PDIF and USB receivers.  The USB receiver sends an I2S signal directly to the DAC without converting to S/PDIF. 

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Quote: 6V minimum - 15V maximum. 12V is usually easy to find.  The higher the impedance of your headphones, the more voltage you can potentially take advantage of.   Linear is quieter than switched - but you probably won't hear the difference.  Switched uses less energy.   The power...