Since these are in my records, previously done hack mod on a Zhaolu D2.5A. Mods encompasses DAC Pre-Amp minor upgrade and more towards the stock headamp unit upgrade.

Change the 4xelectrolytic+4xsmall polyester to 4xhuge polyester caps which i love. these caps are cheap and sounds fantastic! Also bypassed sum unnecassary filter and decouplings in the pre amp since stock zhaolu has a lot in redundancy. Also upgrade the power reseveoir caps for the pre amp board. For the headamp, removed extra decoupling and ground decouplings for feedback loops. The DAC pre amp decoupling is enough for everything, a lot of parts were removed here. Bypassed the first 2 opamps since they are redundant and modded 2xOPA637BP to fit into one dual 8-DIP with a dockable module with extrasss on top. I think that is what i can recall..

Aftermath, ask the owner la..

Ok, here's my final list of opamps:

2x LM4562
3x LME49720
1x AD823AN
1x AD DY2000
1x OPA2107

1x NE5532 (Heed's stock opamp)
2x OPA2604 (ZL's stock opamps)
2x OPA2132 (this will not be free, ijan lend me to play with so you'll have to pay him haha From what i was told, the 2132 performs better than the 2107)

maybe i can post all of them to you, then after you'd picked your favourite opamps you can pass the remaining stash to yuheng

I have quite a handful of opamps with me now. Let me generate a brief impression on each of them.

Equipments: as stated in my siggie

Songs tested:
1. Corrinne May - Angel in Disguise (Safe in a Crazy World)
2. Johann Strauss II/ Josef Strauss: Pizzicato Polka (Denon Hi-Fi Strings XRCD)
3. Pachebel: Canon (Denon Hi-Fi Strings XRCD)
4. Mozart: Sinfonia Concertante for Violin, Viola & Orchestra in E-flat Major, KV364 (320d) (Denon Hi-Fi Strings XRCD)
5. Il Divo - I Believe in You (Ancora)
6. Arne Domnerus - Limehouse Blues (Jazz at the Pawnshop Disc 1)
7. Diana Krall - Black Crow (The Girl in the other Room)
8. Jane Zhang - 我用所有报答爱(The Banquet)


NE5532
- Heed Audio CanAmp's stock opamp
- Bass is thin/moderate. Not as impactful as other opamps I'd tested.
- Huge loss of details, imaging is below average. Good for classical perhaps, coz it kindda eliminates details such as flipping the scores, tapping feet etc
- Vocals are very much cold and sterile. Corrinne May sang as if she just got dumped by her boyfriend. 
- On I Believe in You, you know you're listening from a pair of headphones.

National Semiconductor LM4562NA
- Airy
- Laid-back sound signature, but vocals are a little forward.
- Details are everywhere.  Imaging is excellent too.
- A bit on the dry side, especially on classical.
- Bass is moderate and refined, outperforms the NE5532.
- Not musical. It sounds good, but it is not a keeper imho.

National Semiconductor LME49720NA
- Sounded quite the same as the LM4562NA. It is airy, very detailed and good imaging.
- Bass is stronger and more refined than the LM4562NA.
- Not as sterile as the LM4562NA, a little warm which makes it much more listenable than the LM4562NA.

Analog Device AD823AN
- Bass is strong, on par with the LME49720NA
- Vocals are quite forward. However the AD823 performs exceptionally well on vocals compare to the other opamps.
- A musical opamp. Performs well in classical

Analog Device AD DY2000
- Similar to the AD823AN, it has stronger bass.
- Its performance on vocals is still very much the best among the rest.

BB OPA2107
- Forward vocals
- Warm sound signature
- Narrower soundstage

BB OPA637BP on dual-to-single browndog
- vocals are not as forward as the 2107
- i guess all OPAs inherits the warm sound signature?
- good details, expansive soundstage too
- the most musical opamp among the rest
- hard to stabilize. Having some minor issues with my Heed

Conclusion:
Most detailed award: from NS (i prefer the LME49720NA)
Best vocals award: AD DY2000
Best overall performance: AD823AN

currently sitting in the opamp socket in my Heed: the 637s haha!

walabis bro pls find also the LME49860 and AD8599
u all sifu impression is really useful for all those wanna playing opamp roiling.......

walabies,wats ur ZL version?

What modding must I do to unlock it's potential?
I have Zhaolu 2.5C.
Can u give some recommendation?