The iSilencer 3.0+ iDefender 3.0 is available in my country for about $100.
Will using this combo along with the Micro BL & iPurifier3 improve SQ in any significant way? If it does - for best results - what would chain look like then? ( I will be using my laptop USB port.)
If you have the ipurifier3, not only there is no need for an iSilencer but in my experiments it could even hurt sound quality.
iSilencer is iFi's entry level implementation of the ANC tech, and in my opinion it does change the sound a bit which depending on the situation it can be positive or not.
The more advanced implementation of the ANC circuit ( ipower, DC ipurifier2, etc ) are much better in my opinion, and clean up noise while leaving the sound quality intact and improved.
So bottom line, no need to add isilencer to ipurifier, at best it is redundant at worst could be negative. For example I noticed it kind of flattened the perception of soundstage, if that makes sense.
IMHO this could be because the isilencer has a basic REbalance in it, then the ipurifier has REbalance too, then iFi's dacs have another REbalance tech at their input. Maybe all this rebalancing one after the other could somehow be overkill and end up affecting the timing of the signal a little bit.
The iDefender without ipower could be useful to you if you use your micro BL in battery mode, maybe it could help isolating the ground plane a bit but as far as I know the micro already has isolated ground on the usb input so I'd say it is reduntant too.
But that is the thing with iFi's dacs, they are made to be used standalone, without too many additional tweaks. Not to say that the other gadgets don't work on them, but they work much less than on dacs made by other companies.
So, my advice to you is :
The micro BL is engineered to be immune to most of usb audio problems. To take it to the next level, an ipurifier helps for sure. Next step, you could add ipower AFTER the ipurifier right before the dac.
Next step yet, I think only the iGalvanic could make a worthwhile improvement, and at that point would make the ipower + idefender reduntant too.
"budget" tweak = PC ---> ip3 ---> micro BL
"simplicity endgame" chain = PC ---> iGalvanic ---> micro BL
"ultimate endgame" = PC ---> iGalvanic ---> ip3 -> micro BL (given that iusb3.0 is no longer available)
hope it helps,
regards