@aaf evo sadly the synergy with M5 isn’t that good (at lease for me). E02 does the opposite to M5, it becomes less warm, thinner sounding, and less euphonic vs the pairing with 1Z. Sub-bass rumble is reduced by a wide margin, although that makes the bass sounds cleaner in a way. Mids sounds okay, but I feel that the timbre is a bit off. Treble becomes more pronounced, I wouldn’t say harsh but compared to treble that’s coming out of 1Z, it’s more elevated. M5 treble on 1Z is super silky smooth.
Between low, mid and high gain on E02, low has the most preferred sound for M5. But to me, 1Z is a lot more suited with M5. Perhaps M5 LID tech doesn’t suit DAPs with high power output (this is pure speculation of course), or just the fact that M5 has much lower impedance than Z1R. What intrigues me the most is that E02 has completely the opposite effect to Z1R, it sounds a lot meatier, bass hits harder than on 1Z and treble peaks become a lot smoother. Oh and I even prefer the sound of M5 paired with A01 as it’s not too far off from the sound coming out of 1Z.