DSDs Dual AK4497 Burson V5i + AD8620
VS
Z4 Dual ES9038 TI opa1622 + AD8620
All modded is same way.
1) 3,5mm single ended with Focal Listen 32 ohm - portable over ear headphones.
My DSDs in have better soundstage. Amount of microdetails and clarity is noticeable higher compared to Z4.
Space in DSDs forming triangle in big 3D space. Vocal is closer on the front and single highest female voices sparkles in space surround me. Vivid sound stage is situated far L/R for all instruments. Bass line are presence with good control and can goes deep.
Z4 is polite with a round bubble like smaller space closer to listener. Mid bas is stronger but subbase can't goes as deep as DSDs. Overall darker sound signature Z4 with rolled off treble creating impression of smoother but it's just noticeable less detail and resolution.
Overall fidelity is on side of DSDs.
Z4 is really not recommended for single ended headphones becouse he is working only in a 1/2 of audio rail.
2) Beyerdynamic DT150 250Ohm balanced 4.4mm. There is no reason to listen this from 3,5mm on Z4.
Space have same oval shape but it's bigger than Z4 on 3.5 SE
Control and clarity looks like "2 times" better as well.
Difference with modded DSDs:
Resolution increase without sibilance as sometimes can apire in DSDs in bad or specific recordings.
Sparkles in vocals and hi-hats have more polite character.
Soundstage is closer to listener, especially vocals are places on the front, on DSDs vocal is more around you.
Instrument placement is not as vivid in left-right channel. Fast switching between players sometimes courses "wow" effect on DSDs becouse of space and microdetails. But Z4 is smoother not rolled off like from 3.5mm just softer with nice energy.
Control of subbase is better on Z4 but it's still not as much amount of this as V-shaped DSDs. Z4 have darker signature and it's easier in long listening sessions becouse of linear sound signature and warmth in mids. Z4 have nice amount of mid-base who is missing on DSDs. Just need give a try Burson V5i in Z4.
I'm really don't know how to set up "easy" convertion from VSON10 to DIP8 adapter.
Conclusion.
For 32ohm full size portable 3.5 headphones I would pick up modded DSDs over Z4.
For desktop headphones espacially with big sound stage from factor I go for Z4. For my power hungry designed in late 60's DT150 Z4 is more suitable.
IEMs with wide sound stage sounds better on Z4 as well due to bad for them high output impedance in DSDs.
I'm really need try it with V5i.
There is no clear winner.
Both devices with similar mods have some strong and weak spots.
DSDs can be modified even more in end amp section. In Z4 opa1622 can replaced for DIP8 opamp, but this is difficult and I'm not sure if it's good idea
Without mods I would pick Z4 over DSDs but with mods situation is not as clear.
Good to have both ones.