Which headphones??

Okay, so I'm now leaning towards getting a nice headphone set-up. I am thinking that I'll probably get a couple pairs of headphones when It's all said and done because there just seems to be benefits and negatives about different designs.

Initially, I'd just like to use the headphone amp in my z dac. I am looking at a pair of sennheiser hd 598 new in box for $200 on c-list. These cans seem to get good reviews but I figure I'll want something with a closed design later on so that I can block out exterior sounds also.

I really want something with a great soundstage and imaging, I want it to sound as good as my stereo system, or close to it!

Thanks for your help with this one!!
The most popular and best selling headphone's during the 1970's were the Koss PRO4AAA's. Koss in recent years has resurrected the PRO4AAA due to demand. They are addictive. Very rich, lush, smooth organic character. Ever time I used them in the late 70's I did not want to take them off.
They have that magical quality that transports you into a very musical world. You can buy direct from Koss for $100.00.
I am using AKG 701s (~$250) with an Music Hall amp ($400 retail). Great sound for the $$$. The MH amp is a hybrid design, has 2 inputs, 2 headphone outputs, and can serve as a preamp.
Other headphones from KOSS to consider..but it will cost you. The STRIVA PRO. World's first professional WI-FI headphones with AC adapter. Cost is $450.00 The other set is the KOSS ESP Electrostatics. With large power supply/drive unit with A.C. adapter. Will go up against STAX. Cost is $1000.00. Koss has a very long history and heritage. They made the worlds first full frequency range headphones in 1970. The PRO 4AA. Being around that long and still going strong says a lot. If you want headphones to sound equal to or better than your stereo system, look no further than KOSS. Check out their website.
I use two headphones that compliment each other-AKG 702's, and Hifiman HE400's. The AKG's are very comfortable with a fantastic soundstage. They're a just a little light in low end, but plenty enough for the jazz I listen to. They're more front-row imho.

The Hifiman HE-400's are planar magnetic, and are like having Magnepan 1.7's on your ears, but with a clean bass that leaves you yearning for nothing further.

I run both with a Little Dot MkIII tube amp with great results. Head-fi.org is where I was enlightened on everything "headphones", including a guide for tube rolling on the Little Dot.

The Little Dot can be had for $200, Akg's for $200-$250, and the Hifiman for $400.

Again it's all personal preference, and audition is best.