Gotcha, I am not too familiar with E88CC tube, so I can’t really help you there. Looking at your signature, I am not too sure how much you are willing to spend for just 1 headphone. The Schiit Midgard is “acceptable” to me, but it wouldn’t be something I reached for. My main amp is a Allnic HPA-5000XL using the Supratek Cabernet DHT preamp either using the 45 tubes or 2A3 tubes depending if I want a more vintage sound or a more technical sound. Mine is more of an oddball setup so I wouldn’t use this as reference. The Mysphere 3.2 is usually recommended with mostly a good clean sounding solid state amplifier.
When plugging the Mysphere 3.2 to a budget amp to a more expensive amp, to me the Mysphere 3.2 sounds more transparent amd cleaner sounding. If you manage to find a good tube amp that pairs well with the Mysphere 3.2, the overall soundstage, instrumental separation, and imaging get really better, but honestly I think that’s every headphone when pairing with a good tube amp. But the improve soundstage, instrumental separation, and perfect phantom center stage imaging feels so worth it with the Mysphere 3.2.