dude, you are trying to achieve sounds the A4 is simply not made for
This is what it is made for:
@all: Sorry for self promo again
These thick and bass heavy Pads you are after make use of Unison - a lot, actually (at least in Software). Also, most Synths delivering what you are calling a “warm” Pad have 3 Oscillators, not just two. And dont forget the Effects. Some Synths have built-in EQs which are basically essential in creating their thick sound.
When it comes to Hardware i would say: Get a Novation Peak! This synth is most likely what you are looking for. The A4 is simply the wrong Synth for you. Period!