Where do I go from here?

HI all,

I'm slowly putting a head-fi system together...probably over the next year or so, since my next big purchase will be a new gaming computer, so that my old computer can go back next to my hi-fi where it belongs.

But Intel pulled all the systems off the market so I moved on to project number 2, which is head-fi and I'm a complete newbee here.  After trying a couple cards, I settled on the Ti HD as a source, the Xonar DX is going to go into the old computer as a digital out.  And now I've also picked up a pair of AD700s that I'm mostly happy with...but much of my collection is rock and it just doesn't sound right with rock and I'm thinking about the DT990 (250 ohm).

So I have some questions (one of them is actually amp related):

1.  Is there anything wrong with buying the DT990 for comparisons sake, and sending back the cans that don't make the cut?  I feel back buying two things knowing one will go back, especially something so expensive.

2.  If I just go with the AD700 for now, I'll be wanting to build a system that will allow me to get DT990 (600 ohm) later.  So what amp can I get that will improve the AD700 and ready my system for a 600 ohm headphone?

I'm leaning toward just keeping the AD700, buying an amp, and eventually getting the 600 ohm DTs, since I know the ADs are comfy and its good to have more than one option, but I know nothing about amps.  What would be a good amp to complement both headphones?

Thanks,

BP

PS.  I seriously edited this down...I should learn not to post anything at midnight when I had 4 hours sleep the night before.

Actually, ignore the first part of the question.  All I need to know is what amp I can get that will, for now, complement AD700 and X-Fi Titanium.  Later I want to add the DT990 to the setup.

I guess I'll just wait until I'm ready to buy it and buy both at once then.