AKG K-701 or BeyerDynamic DT-990 used with A/V receiver...Hp amp needed?
First I guess is Sweetwater sells the 250ohm version of the DT-990. Beyerdynamics makes also a 32ohm and 600ohm. Then there is the AKG K-701. 62ohm impedence? Can anyone say/guess if either or only one of these will work well enough from the headphone output of an Onkyo TX-NR609 AV receiver? Even if they will sound 'good' out of the gate from the Onkyo headphone jack, but 'better' with something like a Presonus HP4 headphone amp, if they'll work w/o the headphone amp I can go ahead and buy either the AKG or the Beyerdynamic.
I'm a little confused too about how you'd cable from the headphone jack on the Onkyo to the Presonus HP4 and what cables would be needed. The things I've read about these AKG's sound like they produce an awesome soundstage and instrument detail. I listen to predominantly classical, some jazz, acoustic, & rock. On my classical it sounds like the orchestra will be heard in very wide soundstage while stlll being able to hear individual instruments.
Timmy's correct in that there would likely be no advantage to running your Onkyo into the Presonus unit.
For single-user purposes, I would opt for the lower-impedance version. The "pro" higher-impedance versions are intended for use in situations where they would be paired with multiple headphones driven by the same amp. If run by itself a higher-impedance headphone would suffer sonically compared to its low-impedance counterpart.
I own and have auditioned a number of headphones including Grado, Sony, MB Quart, and Beyerdynamic. My two cents is that the DT990s are the best headphones in their price range.