As you see I highly recommend the Essence ST for the K701. I have own the Heed Canamp and really there is no comparison. I doubt the Essence ST plus Heed combo would work well then it would have to much bass but I wish I still had mine so I could test
K701 on the Heed Canamp have a huge soundstage but it´s thin. The upper treble doesn´t integrate with the lower treble and there is no real weight to the voices if you watch movies or such. But on the Essence ST I am struggling to find weaknesses. Very close to my preferences.
Also don´t listen to the you must get an external DAC. I wonder how many of these have tried other then cheap onboard audio or el cheapo soundblaster PCI cards which aren´t even shielded
. I have tried several external DACs and none of them are better really. And I get no background noise on my Elite Pro, X-meridian, Essence ST etc compared to running my external DACs.
Surely some have better synergies with some other headphones but you can switch opamps on the Essence which you can´t for example on an Elite Pro. If you are listening on a computer you will have to pay way more to get an external DAC at the same level I suspect. And then you don´t get an amp to go with it. Maybe they have longer life span I don´t know... You can see by the size of the capacitors that the Essence surely use quality parts anyway.
Benefit of external DACs is mainly portability. If you get a PS 3 you can use it with that without having the computer running or being worried about ev induced lag. You can move it a long easier to another computer, cd player etc.
But generally you don´t get features like pro logic 2, dolby headphone, sound fields etc without paying multum...