Headphone amps HD what are the choices?


I'm lost a little..pretty new to headphones :p

the headphones out of the sound card i will be getting the is not really good compare to the quality of it's normal line out..the stereo dac that was used + the small amp doesn't give any good headphone justice in quality ( the signal range is pretty bad also)

i will be purchasing HD-580 or Hd-600 in maximum 2weeks

so i'm on the market for a small good quality headphone amp
i need something that will match up good with the sennheiser's and something that will leave the sound untouched as much as possible
i am on a really tight budget
and i don't know anything about headphone amps!

SO this is where YOU knowledge people come into play! I need advice on what to look for, what kind of $$$ will i be paying for what range of quality ( i do not care to buy used at all)!!

Did i say i was on a tiite budget? hihi :)

Thanks all for your time and comments :)
jinmtvt
Post removed 
hi!
i never run any MP3 at all
only CD DVD soon DVD-A and HDCD

and then digital in from PS2 and satell dish

the card will outputs really high quality sound ( waveterminal 192X or terratec dmx 6 fire )

but at that price the amp shouldn't be too much in used
...

what other choices do i have in the used amp market?

and how much will cost replacement tubes?
Generally, depends on your tastes and $ to spend, but I second the MG head recommendation (Antique Sound Labs) - very good headphone OTL amp.

It combines very well with the HD600.
The cost for replacement tubes will vary, depending on what you get. I think I paid about $75 for my tubes on eBay, although you can spend less or more than that.

One thing about the MG Head -- if you're looking at having multiple sources, be aware that the Head only has a single set of inputs -- you'd have to switch cables to go between a CDP and a PS2 or dish, unless you're using an outboard DAC with multiple digital inputs and one analog output for all your sources.