Philippe,
If you have a great DAC already, that is going to give you the biggest boost to your sound quality, so you have an excellent start! Headphones are unbelievably nuanced, and a superb DAC will provide the detail you need.
If you wanted to try out my Allesandro MS2's, I could lend them to you. I might even be in the market to sell them. It would be hard to part with them though...
To be honest, you'll lose very little (if any) money from buying a good pair of used headphones because you can sell them again for the same price, if not more. All of my equipment (except my amp) was purchased used.
My at-the-office setup consists of Sennheiser HD650's and a LittleDot MKII Tube amp. They are fed a diet of lossless & 256kbs AAC and the occasional 192kb Pandora stream. In a word, heavenly.
Word. Senn 650's + Exellent DAC + Tube amp = Utter Bliss.
I just acquired a used Music Hall DAC 25.2 (with the highest level mods from affordable audio) and it just notched up my system to a whole 'nother level. I was lucky to find it. Has a tube in the output stage for the RCA outs, too. Here's a pic, because I know you guys love pictures.
Lights...ON!
Lights....off.
