So, here we go: Source: hm901 with balanced amp card in SE mode except for re600. Findings: 1. 901 is a good dap 2. W4 is still my favorite, especially under this set up. Followed by 334 and k3003 then prolly ie800 (universals) 3. W4 is most custom like with enveloping sound stage, others are big or tall or wide but not like this 4. W4 has better separation, positioning than JH16FP, even though jh16 has better highs and bottom end. 5. Jh16 with original cable is not as enjoyable as w4. 6. SE5way's vocal is not as envolving as w4 to me, other than that 5way is perfect IEM 7. Buy w4 if u like hd600/650 and stop upgrading, u won't find any custom share the same signature but better (certainly not westone's own flagship es5, it is terrible) 8. Don't buy MG6pro, biggest regret in my audiophile journey. 9. Don't throw away a pair of headphone when u first hear it and thought it to be crappy. I originally thought w4 is crappy like 20 dollars earbuds. 10. Every bit is my own experience, take it or not, it is 100% true to me 11. Bought ed8 3 times, sold 3times, try to love them, but the sound is unbearable, worse than EarPods. 12. Senn momentum is no better than beats, most closed ones are actually, very 2D. B&w p7 is better than momentum and ed8, more enjoyable to me at least, by no means good though. W3000 and th900 are good closed cans along with d7000 Oh forget to mention, both re400 and re600 sounds very 2D, even though their tones are tuned nicely. No sense of space what so ever. Re600 with 901 in balanced mode to me is inferior to w4 or jh16.