Yes, you have the DSP amp if you have the DSP option in the menu on the head unit and not the door amps. Door amps are roughly the size of a fag packet, only slightly smaller than the door outstation. DSP amp is tucked away behind the sound deadening behind the sub on the LH side of the boot. To fit an aftermarket head unit you have to bypass the DSP amp and add two pairs of speaker wires for the rear channels. With the DSP system, only left and right channels are sent to the amp with the fade between front and rear done in the DSP amp. All speakers are wired back to that and not to the head unit. Like the door amps it incorporates crossovers to split each channel between the bass speaker and the mid and high range speakers. You can jumper the left and right front channels from where they arrive at the DSP amp directly to the outputs that go to the speakers but to match the speaker impedances stop the sound quality going 'muddy' you need to put crossovers in those jumpers. That way, taking Left Front as an example, you'll have a pair of wires arriving at the DSP amp from the Front Left output of the head unit and two pairs of wires from the DSP amp to the Left Front door, one pair for Bass and another pair for middle and top.
i did this https://rangerovers.pub/topic/8-info-p38-alpine-dsp-amp-connections-and-wiring?page=1#pid30814 as a result of being asked about it on RR.net (but didn't publish it on there, why let them be the source of useful information after they removed all of what was there before?) and the guy managed to do it himself and got it all working.