[msq123]

I am looking for some advise on selecting the amp, I searched all over the forum but couldn't find specific answer I was after. Could someone here help?

My M5 has 676 HiFi audio. I recently upgraded front door speakers to Focal K2 power ES 100 K with Dynamat sound deadening.

I am now looking to go for the second step where I replace the amp to power these and stock subs for the time being but later upgrade to Earthquake SWS 8x or FocalIFBMW - sub so amp needs to be powerful enough to drive these.

Now the dilemma, I was looking at JL Audio XD400/4 V2 which I am getting a good deal on but one of the installer I spoke to advised me against it saying it might not be powerful enough for the subs I am looking at (he was specifically talking in red to earthquakes) and instead advised me to look at XD500/3V2 which has a dedicated sub channel and is more powerful than bridging the 2 channels in the sub I was looking at.

I thought that any of these amps could drive under seat 8" sub @ 4 ohms efficiently but he didn't agree so I want some informed opinions before I purchase the amp. I prefer the 4 channel but don't want to be underpowered when I eventually change my subs.

I hope someone here is familiar with these product lines and would be able to help me? Cheers