Thanks for the review. I own RE-0 so based on many review I suppose RE-400 are quite improvement. I wonder how RE-400 compares to DBA02 / Brainwavz B2. I suppose the bass extension would be better on re-400. How are the other aspects like details / imaging / resolution / speed?
RE400 is a more rounded IEM. But if you like RE0 sound signature then I won't call RE400 a direct upgrade. I don't think you will find those aspects you have mentioned to be any major improvement, if at all. The biggest improvement going from RE0 to RE400, beside the change in sound signature, is the increase in mid and bass texture and thickness.