[2wheelfan]

I will preface by thanking all the music buffs and audiophiles here that contribute knowledge to help those coming into the hobby.
Some of us are late bloomers ...I am 58 and purchasing my first good quality heaphones...how about that?
After consuming copious reviews here including digesting all related jargon which I mostly follow as a tech head but well out of my area...I settled on subject phones.  I couldn't be happier.  Am listening to Patti Griffin as I type this.
 
A quick review of my modest setup.
- Home built PC with ASRock 970 Extreme4 ATX Mobo with stock on board sound card.
- 3.5 mini jack out to RCA inputs into older receiver.
- 1989 Sony STR-AV710...that's right...1989
- Windows 7 64 bit Itunes 10.0...pretty extensive collection of classic rock, country, some classical...blues..alternative etc.  Recording quality varies...but many are lossless format...but a real mix.
 
I have to say, I am blown away.  I didn't expect to be.  But I am hearing detail in songs that I didn't think was there.
I thought perhaps lack of detail was due to the front end aka quality of Itunes or on board sound card.  Not so.  Needed more back end aka better amp and headphones.  On board sound card DAC btw seems fine.  I have an optical out on my sound card but no optical input into my old receiver. 
Tweaking the EQ's in both Itunes and receiver to embellish the already warm signature of the DT-990's which likely work well for boomers with some high frequency hearing loss who listened to too much rock when younger, it sounds fantastic.
 
I had already read about upgrading to Dolby sound card...Async DAC's...dedicated headphone amp etc...but I have to say, for the non audiophile like me, this is a great combo as is.  Special thanks are in order.  Thank you to MalVeauX for your even handed advice and all the help you provide here.  Same with PurpleAngle.  MalVeau's advice supported by PA about using a old AVR as a headphone amp was spot on.  Many disagree but my experience agrees with Mal and PA. I deliberately chose the 600 ohm model of DT-990's for the great damping and man am I glad I did.  These aren't even close to burned in yet but god they sound good.  Volume on Sony AVR only set at 1/4...don't need tremendous voltage apparently to drive.  They even sound pretty good straight ouf of my PC...or even Ipod if cranked a bit.  I expected the 600 ohm model would take more juice to drive...but not so. But amped?...they come alive.
 
There are much more complete and comprehensive reviews of the DT-990 on this forum...but wanted to share my observations for those considering their next purchase.  I wanted the 990's for slight high and low frequency augmentation and wide sound stage...in contrast to more neutral and perhaps more accurate 880's. 
 
Other observations about the DT-990 600 ohm include:
 
-Very light weight.
- Comfort is hugely important to me....and my head is sensitive to clamp pressure.  The DT-990 Premium as reported has a very 'fair' amount of clamping force.  I wear size L hat.  I don't feel a need to adjust clamp pressure at this point.
- Ear pads are very 'pillowy'
- Aesthetics are very nice.  I like the look of the headphones.
- I prefer a straight cord coming out one side which the premium model has.
- Screw on 1/4" jack is a nice touch...and what I plug into my receiver.
 
Best Regards.