Originally Posted by trippinonprozac
Thanks for your input.
Do different opamps assist in the amount of power to drive the headphones?
I just want to make sure I give my HD 650's everything they need.
The list of opamps in the PDF is nice, you should additionally consider OPA827, OPA602BP, OPA209, OPA228, OPA1641, and OPA1612 to the list.
LM4562/LME49720, 827, and 1612 need extra psu bypass capacitors to truly shine. It's identical as what others do to the Audio-gd opamps using Mundorf or Russian PIO capacitors, if you've read about that.
I would personally pair HD6x0 with OPA827 or OPA602. Clear, neutral chips with excellent soundstaging, 827 a bit more so than 602. 827 is a bit fuller in sound than 602. The low bass is lacking in 827 without at least a ceramic byapss cap. It sounds best with a ceramic + Vishay MKP1837 caps. 602 sounds best with a ceramic + 10uF tantalum caps.