Good points. I didn’t pay much for mine. As I say I only found ONE type of tube that made it sound very good. ALL the other tubes I tried were good-to ok at best 
Interesting. I think we have [over all] fairly different sounding characteristics of headphones
So on another level Im interested to learn your experiences
Admittedly I use the LDT1+ for a relaxed musical enjoyment whilst the I use the 02 for a more reference experience. I have another 4 or 5 amps all of which of course work better with some headphones than others… but Im sure we all know that here 
As others mention, there can be so many components in ones audio chain all of which can make a tiny to huge difference in sound
Ive been enjoying mostly 600 ohm flagship type 1980’s headphones with the LD1+ which certainly seems a nice synergy
@Torq - We are just politely chatting. Relax xXx