I have a pair of Sennheiser HD650s, and am about to order a FiiO E12 Montblanc for it. I'll be pairing it with an iPod Classic via line-out for now but will probably get a better media player soon.
I listen to a wide array of music - classic, metal, classic rock, hip-hop and electronica, and am looking for a comparably priced headphone which will have a different sound palette with this system and complement the HD650s. I dont like bright headphones or enhanced treble. I do like headphones with a great dynamic range, superb transient response, and solid, deep, tight (not boomy) bass. Will the Hifiman HE 400s give me this sound or do I need to get to the HE 500s for this? Or any other recommendations?
Re my other gear, I have a pair of Sennheiser HD518 for travel, and I also use a Bose (yeah yeah, I know... it was the only one i could find in the airport dutyfree) headphones at work, but have ordered a V-Moda M80 for office use. I use these with a Galaxy Note 2 and with my laptop.
Would something like a FiiO E6 help with the sound here? I'd prefer to have a separate set of gear for travel use and home use.
At some later point, I am considering upgrading to a high-end, summit-fi headphone system.
Re my general tastes: I dont care much anymore for audiophile hair-splitting (I got over those tendencies over a decade ago after I got a 2A3-based system; my Stereophile approved solid stage gear all got sold soon afterwards). I havent listened to my Reference Recording CDs in over a decade, my favorite classic music CDs are mono recordings of Toscanini and Furtwangler: in other words, I listen to music, not audio. And I love the rich, warm single-ended tube sound.
Given these preferences above, how much of an improvement will I notice if I spent $2000-3000 on an amp/headphone setup? Or should I leave that for the golden ears and stick to this setup? I know this is a fairly subjective question, but opinions would still be appreciated. For regular audio, I kinda know what my sweet spot for price/performance is; I dont really know what that is for headphones, so am trying to get a sense.