subs lost some oomph

I have an alpine head unit, with the 4V sub pre out, an Xtant 1000A wired off a 1 farad cap, that's supplied and grounded by 1/0 gauge cable. The Xtant is not even a year old, and neither are my two 4 ohm dvc solo baric L7's, that are in a custom built box with the right volume. The L7's are running bridged 2 ohm. I was cruisin, running them pretty high as I always do, and have never had a problem, when the bass dropped off by about 20%. It was kind of a soft, swift drop off, and the only thing I can attribute this to is maybe the 4V pre's lost some power? The HU is about 4 years old and has endured plenty of use, but I can't figure it out. Any help would be greatly appreciated! Thanks

Sounds like you lost a voice coil in one of your subs.

I'm assuming the blame for that is that I like to run my subs at high power most of the time Then, I assume that there's nothing I can do but try to get some sort of warranty work/replacement? That's what I was afraid of. I can find out if it's the voice coil if I check the impedence with a dmm, can't I? Thanks for your advice.

just hook up each voice coil individually to your amp, , if they all play then there fine.2003 Chevy Avalanche,Eclipse CD7000,Morel Elate 5,Adire Extremis,Alpine PDX-4.150, 15" TC-3000, 2 Alpine PDX-1.1000, 470Amp HO Alt.

Use a DMM and check for continuity for each VC.Memphis MC-1300

2 12" JLw6v2

Diamond audio M3 6x9

Diamond audio M3 5.25 components

Audio control Matrix

Carputer

Thanks everyone for your input. Turns out that one is shot, and the other one is clipping. Thanks for the input.

BTW i agree with all the opinions here if that helps lol---- 1996 Chevy S10 ----

1 Lightning Audio S2.600.2 Amp

2 Lightning Audio 12" Subs

1 Lightning Audio 1 Farad Cap