Ok, guys.....
Here is very long while since my last post into Head-fi....
Totally what I did into each mods are reinforcing power supply (both digital/analog) and making lower noise floor around 9028's, replacing I/V resistors, stabilizing GND (stocked AMP6 were awful), and affordable capacitors, better TCXO's.
But I'm doing just up to one's requests or sound preferences.
As seen in several AMP board mod examples on the web, they are replacing Nichicon FW's to another's...however on that position and connection, audio grade caps are not effective(even though officially iBasso uses).
Reason why is very easy to be explained, the stocked FW is connected to main battery power bus, so that leads to DC/DC's supply and not directly connected to analog +/- powers or digital buses.
On that position, capacitor should be selected lowest ESR and capacitance first (e.g. SEPC or HZ 6.3V class, in parallel with tantalum makes better)
And blank pads aside of FW are the most effective position +/- analog power bus and recommended to use audio grade caps in AMP1....but examples like those are unseen....
Also, iBasso loves to use LT3471 since DX100 but the stuff scatters huge noises in 1.1MHz and requires to add countermeasures.
My mods are already solved or suppressed these issues.
Prices are up to one's requests, so just ask me via email or PM me....