So I'm a little confused about how to properly set the gain on the setup that I am going to install in my car. I watched a video here that showed me how How to Set Your Amplifier Gain to RMS Power Using Ohm's Law - YouTube. easy enough to understand, I think...the amp that I bought is the RF T1500-1bdcp and I am going to be powering two T1D412's if that matters. So the rated RMS of the amp is 1500 and @ 1Ohm I am going to want to be looking for about 38.73V with the meter and test CD...But then I saw this video about how to set the gain in reference to clipping PREVENT CLIPPING! Set AMP GAINS like a Pro! New SMD "Distortion Detector" - Coming SOON! - YouTube. The guy on the first video said something about line level out supplies clean power throughout the full spectrum of volume...the guy on the 2nd video experienced clipping at sound level 59 out of 62 on his head unit. I would imagine if you hooked up a oscilloscope to the first guys setup he would experience clipping? The 2nd guys setup did not mention anything about volts or watts or anything? If I set it up with a meter at 38.73V is there a chance that I can still damage my speakers? BTW I have a cheap sony MEX-BT39U head unit, IDK if that matters and if it has a true "line level output"...whatever that is but it says something about pre-amp output relating to LPF/HPF. Should I get a HU without the pre-amp output? OK sorry for writing a book but now for the dual battery setup questions. Can I use two "stock" batteries because that is within my budget, instead of buying two totally new deep cycle, heavy duty super duper batteries. I'm assuming two stock batteries would still increase my amps/volts? Also I ran the 0 gauge to the back already so can I just run that to the 2nd battery and then run a ground wire from the 2nd battery to the chassis, instead of running it to the negative terminal on battery number 1 or is that a no no? One last question and then I'll stop...I promise lol. I already bought a capacitor and I know that y'all probably highly frown on this but I bought it before I knew I could do a dual battery setup. Is there any reason I couldn't run a dual battery setup and a capacitor? Thank you very much for your time.