95 Sls Audio System Problem

so I had a dvd player installed a month ago at cartoys. When I had the dvd player installed I also had them install the subs and the amplifier. The dvd constantly continues shutting off while I drive or even when the car is idling. The dvd player shuts off and then starts up again by itself. Another thing that I noticed is that constantly now, I keep on getting the "service the vehicle soon" on the display and "anti-theft system problem" as well. I don't know what do to. Cartoys told me that I need an ew alternator but I had it checked and it seems to be working beautifully. The voltage shows that when the car is turned on and the dvd player is working the voltage drops down and then if i turn the the climate on the voltage drops down again to about 12.3 or something. Is this normal? When I play the dvd player and the subs the rmps go up and then down and the lights dim as well everytime the subs hit. I have no idea what to do and it is really frustrating. Any help would be appreciated. thank you in advance.

Your voltage should be high 13's to 14 volts at idle. It sounds like that alternator isn't that good. Also, how good is the battery, and the cable connections?

I just got a new battery at shucks a week ago so I'm assuming its in pretty good conditions. I don't know if the cable connections are good, i have no idea how to check that. thanks

I recently upgraded my 93 sts with new custom exhaust, passive struts, MB drifter rims, and new pioneer 5900 head unit with total mobile amp and 12" pair of planet audio subs. Rigth after doing this complete over haul on alot of items I felt needed improvement from stock, I replaced the battery with an optima yellow top, then moved on to the alternator.The typical charging voltage should be around 14.3 to 14.6, and this is a stock unit.With all the elctrical and parasitic drain for those systems even when the car is off, it is wise to add a 1.5 farrad capacitor to the sub/amp combo, make sure that the pipe line (aka power and ground wire are at least 4 guage) to accomadate this free flow of new equipment. The next thing that I would adrress is how the new head unit ws integraded into the factory existing stereo wiring. I personally leave the bose controller in the trunk stock and use my aftermarket pre-outs front and rear to transfer good signal to the bose controller that goes to the factory speakers and amps. That also leaves the regular high level outputs for and additional 4 speakers to be added without amps for those channels. This gives you more flexabillity to tweek your custom sound system. If you would like to know more give me a yell I can help with cadillacs of this generation, electrical and mechanically.