I recently changed the cable on my iBasso SR-1's to a 6nines Silver Plated OCC cable & I am absolutely head over heals Gaga in lust/love with these headphones..
I've spent a lot of time & $ over the last year driving hundreds of miles to Austin,San Antonio & Houston auditioning TOTL's from Audeze,HiFiMan,Focal & Sennheiser..I've still yet to hear ANYTHING that has the naturally organic tone of the iBasso..Honestly they sound like iBasso invited a pair of Harbeth M40.1's, a Cary Audio 300SEI amplifier & an un named,Class A,KT88 Ultra Linear amplifier to a motel & threw a drunken orgy,culminating in the birth of a step child with the voice of all the angels in heaven..
They don't need a special tube amp to thrive either..As a matter of fact,they are NOT really suited to a tube amp that is voiced to be warm & tubey,they would sound like an older Conrad Johnson tube amp then,syrupy & sloppy...
They ABSOLUTELY LOVE Class A Solid State.. Driven by the headphone out from my SimAudio 240i or a Topping DX7Pro DAC/Amp,they simply drip & oooze tonal color & saturation..
They don't have quite the massive standing & imaging of the Sennheiser HD800S,or the super deep slamming bass of say an Audeze LCD-3/5,or the razor sharp,super extended treble of an AKG studio headphone,what they do have is a balanced tone that makes them a superb all arounder,favoring no specific style of music & giving hour after hour of fatigue free,blissful listening...
I know I know,everyone hears differently & I'm coming off as if my sub conscience desires have over ridden my analytical brain but I am NOT easily impressed or swayed by any piece of gear,be they audio,video,amature astronomy,automobiles,whatever...It's SOOOO very rare to find a piece of audio gear that,with a bare minimum of tweaking(changing the cable),can compete with the absolute best of the best...I would pay good $ to get a few golden ears who own TOTL cans from ANY manufacturer together for a blind listening session with these headphones..I have ZERO doubt,more than one of them would walk away shaking their heads after finding out what they were actually listening to...