http://www.moon-audio.com/headphones/sennheiser-headphones/sennheiser-hd-700.html   You can preorder them through Drew Baird.

I think they are. But they are single so you need 2 per on an adapter.

I'm using the 650's with the xonar essence stx also. If you really want to give your card a boost you should replace the op-amps with 3 of these. http://www.ebay.com/itm/DUAL-SOIC-LME49990-DIP8-ADAPTER-/190641930863?pt=LH_DefaultDomain_0&hash=item2c6325026f#ht_1039wt_1396  or 3 of these...

I think the screeching noise maybe due to the videocards audio drivers. Just don't install those drivers, it gives you a choice. I have windows 7  64 bit and have never had a single problem.   i7 3930K Asus P9X79 Pro Corsair 32gb (4x8gb) Corsair 1200w psu EVGA GTX 580 Classified

Upgrade the op-amps to LME49990's. You can get them on the adapters on ebay. 2x each adapter. It is amazing, trust me.

After upgrading my op-amps to the LME49990's, Techno Rave from Blade is awesome now.

I just now read some of the things in this thread. I have a friend who bought the crappy Beats. He asked me the same thing until he listened to mine and he wants his money back.

You will need 2 per adapter, which is six total 49990's. Trust me, they are only half the size of the dual's, its better to buy them already done, and the guy that built them did an excellent job soldering them, its well worth it.

It needs an adaptor, its a single soic when the card takes dual's. The cheapest way to get them is through the ebay link I posted. Or just buy an adapter and the 49990's and solder them yourself. They are tiny though and my hands shake, too scared to do it myself.

Okay, I installed the 3 sets of the LME49990. My verdict is its UNDENIABLY THE BEST OP-AMPS EVER! The bass is amped up to new heights, but the music is even more clear. The detail is amazing. Only thing is DO NOT USE THE SAME VOLUME LEVELS YOU ARE USED TO. If you do it will blast your ears off...

It has to be the stupid power saving features built into windows 7, sometimes it provides way too much power to the pci-e slots. Just turn that off and it should never happen.

I just ordered 3 of these, when I test them out I'll let you all know how they perform.   http://www.ebay.com/itm/190629659561?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649#ht_1039wt_1396

Here's how mine is setup and it has no noise. Under Control Panel- Hardware and sound- Playback: Asus Xonar Essence-Default Device. S/PDIF: Same. Under sounds it is the Windows Default. Also check your cables inside your comp. You could have the Realtek front panel audio cable hooked up to the...

I also have an upgraded cable, that'll probably make a difference in the audio with these settings too.

I have mine turned off, I think it makes it sound terrible. I have my settings on 8 channel, PCM 192 khz, effect is Padded Cell- S-Rock, Flex Bass is 150hz, HP Large. With these settings and upgraded op-amps on the 650's music sounds amazing.