Hey! This is a question for me!!!!
I have a Toshiba 3950 connected to a
Musical Fidelity X-10v3 connected to a
Van Alstine T7 which has a headphone jack.
I have HD650's.
I have a DAC1.
I don't do much headphone listening, but I checked out Michelle Shocked's remastered Short Sharp Shocked and equalized the volume between the two rigs, switching the headphone jack as quickly as possible.
And...
They both sound good, I want to say the preamp setup is marginally better than the DAC1, especially because I'm trying to be a "tube" kinda guy. But one thing's for certain: the equalized volumes translates to 1:30 PM on the clockface Van Alstine preamp volume dial whilst the DAC1 is at 9AM!
I can't imagine you'd need a separate amp to drive the HD650's, at least from a volume standpoint.
biz