Help me choose a multichannel soundboard, sound quality on focus.

[upking]

Hey guys, what's up?
Recently I've been looking for a 6 or 8 channel soundcard.
Doesn't matter if it is PCI-Express or USB
My goal is to achieve the best audio quality for a new diy setup, that is going to have 6 or 8 DIY speakers and also DIY amplifiers.
Why multi-channel instead of stereo?
Movies and games, they're an essencial part of my "PC entertainment". Even though music is number one in the list.

So I've searched arround and came up with some options:

1.ASUS Xonar Phoebus
2.ASUS Xonar D2X

Also I've taken a look at the Xonar ST + H6 which would give me an excelent 7.1 sound, however the ST is a PCI card, many new motherboards are coming only wih pci-express slots, so I don't wanna take the risks ('cause I'm looking forward to buy a new pc, probably by the end of the year.)

Creative gave me some good looking boards like Sound Blaster X-Fi Titanium, Sound Blaster X-Fi Surround 5.1 Pro, and others but I couldn't manage to get their specification (THD and snr)

Focusing on the Asus cards, the Phoebus gives me the possibility of using an 600 ohms headphone with good quality sound (it's not my objective right know but who knows about the future) in other hands all the channels except the frontal L/R have more THD than the D2X.
0.00039% (-108dB) for Front and 0.00063% (-102dB) for other channels in the Phoebus and 0.00039% (-108dB) for all channels in D2X
Also the input THD is better in the Phoebus.

After all I can't decide which one should I go, now we come to the price topic

.Phoebus 200$
.D2X 166$

What do you guys think? Also I'm open to new suggestions, the only requirement is the 6 or 8 channel output to my movies and games.
Thanks for you help, wish me luck in this new adventure, 'cause I've got lot of things to build. Hahaha!