IMHO, the breakdown of sound quality percentages for listening. This assumes good quality equipment.
source quality: 10%
cables: 1% (Monoprice cables or better)
Power Supplies: 1%
DAC: 3%
Amp: 3% (includes the benefits of balanced vs SE)
Headphone cable: 2%
Headphones: 80% *
* pads can make a significant difference
Obviously YMMV, except for very well trained and sensitive ears (youth helps), this is probably true. True audiophiles are always trying to squeeze that last 1% or less out of their system. We always head about the law of diminishing returns, and it it absolutely true. It's early easy to get to the 95% level with 500$US headphones and $500US of electronics.
The said, the Jodie does seem to power some of my harder to drive headphones well, like the Ether C and the HD800. I haven't tried the T1 as I loaned it to ColtMrFire, but I'll get it back too. I still need to more comparison listening to draw conclusions, though, but initial impressions are unless you need more power to
drive hard to drive headphones, benefits are minimal if you already have a good amp. I will also compare it to my iCan Nano, and I might bring home my 1st get Magni, but that is a lot of wiring headache.