woah, been awhile since I found someone using the same receiver as me! I find the "Silent Cinema" headphone surround feature a little echo-y and underwhelming, what do you think?
The Foster headphones you have can REALLY scale up with better audio-chain gear. The frequency measurement charts have a bit of a V-shape, with mildly accentuated bass and treble. And I'll tell you what... weaker amps can leave it sounding "ok," but thin and less punchy ththe full potential. I heard them on a "transportable" desktop amp at a CanJam, and it was alright. Then I plugged the same headphones into Fostex's flagship $8,000 amp next to it (with tubes and stuff), and that made a DRASTIC difference! Full-bodied mids and bass, smooth bright highs (not too bright, just clear and "shining"), and haunting vocals. The track tested on both amps was Radiohead's "Weird Fishes/Arpeggi." Now, for good results, you don't have to spend $8k, but the headphone's performance does continue to rise.
The above, plus the TH-X00's sensitivity of 94 dB, means my first recommended upgrade for you would be an amp. The Schiit magni, Schiit Jotunheim, and Objective 2 are popula, well regarded amps, but they are a bit more clinical-sounding; not my recommendation for you because they could bring too much attention to the highs and be pushing you further in the opposite direction from what you enjoyed about your Oblanc. I'd recommend a tube amp by Garage1217, like a Project Sunrise or Project Spark, or a solid state amp (can't tweak the sound by changing tubes, but less hassle and less subject to EMI) like Cavalli Audio's upcoming Liquid Spark or something from Meier Audio. When you are ready to upgrade the DAC too, right now the Schiit Modi Multibit (MMB, nicknamed "Mimby") is a really hard to beat value.
But really, an amp upgrade will noticeably help the TH-X00 (Anyone else think "THX," like the movie audio company?) pull ahead of the $20 el cheapo headphone you have now. Aaaand, if you decide you don't like audio much after all, the resell market is decently strong (imo stronger than computers and smartphones). GLHF!