In my opinion, I would advise against selling off your speaker system to buy a state of the art headphone system. I have some of the best headphones made today (Stax SR009, Audeze LCD X, HiFiMan HE6, LA7000 and a modified AKG 340) and I enjoy them for late night listening so that I don't disturb my daughter's college studies. I've been into high end headphones for the last 16 years and I've owned just about all of the top cans and some of the top tube and SS headphone amps (Eddie Current Zana Deux SE, Ray Samuels DarkStar, Cavalli Liquid Fire, Luxman SQ-N100). That said, I still rather listen to my speakers by far.
My speakers create a soundstage that even the best headphones can't match. The SR009 are great but depending on the recording, they may not be my first choice. You need to listen to them and some Audeze orthodynamic cans like the LCD X or 3F. The Stax and Audeze sound quite different and which you prefer depends on your preferences. Also, like a previous poster stated most of the top headphones are open so they will leak sound. There are some really good closed cans such as the Audeze LCD XC and the Fostex TH900. You may need closed cans if family members will be in the same room while you're listening.
I recommend that you try to integrate a headphone system into your speaker system like I have done. My A10 preamp also serves as my electrostatic headphone amp for the SR009s. If you decide to go with dynamic headphones instead of electrostatic, you'll have more preamps and integrated amps to choose from. There are many headphone amps that are excellent preamps. A few that come to mind are: Apex Teton, Manley 300B, Ray Samuels B52, and some of the Woo preamps. Also there are many integrated amps that are great headphone amps such as the Cary SLI 80. If you're able to integrate the headphone and speaker system into one system, then you can have the best of both worlds.
My speakers create a soundstage that even the best headphones can't match. The SR009 are great but depending on the recording, they may not be my first choice. You need to listen to them and some Audeze orthodynamic cans like the LCD X or 3F. The Stax and Audeze sound quite different and which you prefer depends on your preferences. Also, like a previous poster stated most of the top headphones are open so they will leak sound. There are some really good closed cans such as the Audeze LCD XC and the Fostex TH900. You may need closed cans if family members will be in the same room while you're listening.
I recommend that you try to integrate a headphone system into your speaker system like I have done. My A10 preamp also serves as my electrostatic headphone amp for the SR009s. If you decide to go with dynamic headphones instead of electrostatic, you'll have more preamps and integrated amps to choose from. There are many headphone amps that are excellent preamps. A few that come to mind are: Apex Teton, Manley 300B, Ray Samuels B52, and some of the Woo preamps. Also there are many integrated amps that are great headphone amps such as the Cary SLI 80. If you're able to integrate the headphone and speaker system into one system, then you can have the best of both worlds.