You raise some ideas that contradict the original ideal of high fidelity and my own sonic ideals. There are no sound transducers that reproduce transients too fast and have too much control over membrane movement. Quite the opposite: All existing transducer principles have the problem that their membranes can't follow the music signal fast enough; it would require zero moving mass/inertia and an acoustic environment free from reflections and resonances – hence a physical impossibility. So we already have to accept a slower decay than desirable and some unwanted sustain after each note. And now you want even more of it and are trying to find a method to artificially make the sound even more inaccurate in terms of the timing behavior! I'm convinced that you would be heavily disappointed about the result.
The impression of an overly dry and fast bass is often coupled with a somewhat elevated upper bass (105-160 Hz) and a roll-off down to 20 Hz. The FH7 suffers just slightly from said roll-off, actually less so than most contenders, and its upper-bass emphasis is virtually nonexistent. At least that's how I hear it with my ears, which is reflected in below EQ curve (from FiiO X3II, with FiiO pure silver cable):
I also wonder how you can perceive the bass as too strong – most here have reported a slightly underrepresented bass, if anything. To my ears its low-frequency amplitude response is close to perfect, it just can use a slight low-bass boost. Maybe that's in fact the remedy for your problem, too, since a slightly dominant low bass with reference to upper bass usually leads to the perception of fullness and even slowness. Have you ever tried foam instead of silicon tips? They're reported to offer better bass extension, i.e. increased low bass. Moreover one crucial advantage: They absorb high frequencies instead of reflecting them within the cavity between ear drum and driver. Of course this leads to reduced treble intensity, but keep in mind that all that's eliminated is the artificial sustain created by the reflective silicon surface. Although this may contradict your original concept, I'd say it's worth a try. (In my book it's even a must.)
There's actually one thing that supports your wish for reduced dryness: the fact that the music we usually listen to is meant to be heard through speakers. Headphone listening lacks the additional reverberation contributed by living rooms in the case of speakers. However, artificial sustain isn't the solution for this issue – it would only muddle the sound and severely compromize transparency. What you need (if you can't live without it) is a life-like artificial reverberation. That means the original signal still has its sharp starts and stops, whereas the reverberation follows a few milliseconds later. It's nothing I would really recommend, because the added reverberation masks a lot of the spatial information (particularly depth) on the recording. What I really recommend instead is a feature I can't renounce myself: Crossfeed. It's an important tool for overcoming a decisive incompatibility between speaker-based recordings (hence virtually all) and headphone listening: low-frequency channel separation. You'll be surprised how more realistic and comfortable music will sound with a good Crossfeed (à la Chord Electronics or Meier-Audio). Also, it may absolutely contribute to a fuller, warmer bass reproduction in your sense.
