my pk1's 3.5mm plug was broken so i cut it of and i see there are 4 wires. does that mean it is posible to solder   balanced plug like for protector amp? two of the wires are copper in color others are red and blue.   or maybe i want to make a new 3.5mm plug .   is it difficult to...

there are apps for smartphones that measure noise in decibels, for example SoundMeter , (i also had similar for symbian phones). and when you have new headphones, just put them close to iphone's microphone and play some test tones (for example 30hz,40hz,1khz...), write down db figures from...

wanted to measure burn in with equal loudness and here is outcome (used ibasso t3 amp, hifiman re252, hifiman re0 iems)

if you like the color : Newegg.com - SONY Walkman S Series 2.4" Red 16GB MP3 / MP4 Player

So you want to know if your gears produce good soundstage - then please get Psychic TV's song 'Always is always' from Dreams Less Sweet album. If you have good gears, you will hear a priest walking in a nice circle around you. If gears (headphones, amp etc.) lacking, you will hear that priest...

my phones don't like women voices, i think some portable amps can equalize this?