Hello I bought the X3 a week ago and now reading up about ohms , resistance , voltage etc it makes me question what type of headphones I should use with this device.
HD 558 w/ Foam mod
fostex t20rp mkii (non modded)
Fiio E7 (with no Aux in jack - it broke so only USB)
Questions! (Warning they may be stupid ones I'm still learning here)
Assuming impedance is ohms, dividing headphone impedance by 8 is the maximum ohms you can give the headphones without loosing any degradation?
Does the X3 & E7 auto detect the correct power , voltage , impedance? and is it always most accurate (if not is there anyway to control it?) or is it depending on volume and low-high gain.
Before playing a song on my X3 always hear a small click, this happens everytime a song changes or new headphones are plugged in.. Something to be concerned about or not?
My Panasonic RP-HTX7 sound just as loud on my X3 as my E7 (e7 using USB), Why?
The X3 / E7 cannot power my fostex t20rp mkii at any decent volume. My dead JVC receiver which was made in early 2001 was the only unit that could make them vibrate and sound LOUD (volume control went from -100db to 0db) and loud was at -5db before it distorted. They also made my HD 558 vibrate so much that it was hitting the plastic casing. The question here is what receivers / amps are recommended for these headphones to output really loud volume like my JVC? Would really like to hear my Fostex again but nothing can push them!
I don´t know the other headphones you mentioned but I can confirm that the HD-558 sounds very well on the X3.
The FiiOs usually have an output impedance of less than 1 Ohm. So they will drive every low-impdance headphone - including IEM - without changing their frequency response. High impedance cans like the HD-600 will be driven equally well. Not by the E7 but by the X3 (-> high gain activated). The amp of the X3 is extremely powerful.
The small click on the X3: do you mean a click in the audio output or on the device itself? In case of the latter, it´s a relais inside the X3 that un-mutes the output (actually, there should be two clicks).
Regarding your JVC receiver: it could very well be that it not only was extremely loud but also quite unstable. Headphone outputs on older amps like yours (or my own Sony) have a ridiculously high output impedance ranging from 100-200 Ohms. Not only will that create a very audible frequency error on headphones susceptible to this (like your HD-558), the output will also loose control of the diaphragm, leading to the creation of distortions. They could have been responsible for the vibrating shell of the your Sennheiser.