For what the E9 is, it's great. But I more or less agree with you - there are incrementally better options, but most of them cost considerably more. If I still had my 701s, I'd be curious about the Asgard with them as well. The best pairing I tried was also the last setup - the full stack with the 200wpc amplifier driving the headphones and a Technics DtoA acting as the preamp and decoder. Good channel separation + volume tracking is really the key. Having "enough" power is beneficial too, but they're not nearly as hard to drive as many people make them out to be (and remember, the E9 will drive something like 1W into them).
6 meters from a closed door (that's like 20 ft?) with the 701s should be no issue unless you listen at hilariously high levels. Like ear-damage high.