Generally speaking, low impedance cans are current driven, while high impedance cans are voltage driven
The Little Dot I+ is specifically designed and optimized to drive low impedance headphones like Grados.
Low impedance headphones require high current output to sound their most dynamic and impactful, and the Little Dot I+ provides this as well as a touch of tube warmth.
I own the LD1+ and it is wonderful with my RS1i & SR60i...for the price, I can't recommend it enough....great little amp with the option to roll tubes and opamps....makes it a great bang for the buck.
Thanks for that... I was going to opt for the MKIII due to it being a newer revision, but if the LDI+ is recommended, then that is what I shall go for :)
Plus it's cheaper :D