Looking for that thump w/o frying the sub

I recently purchased a new Alpine MRD-M605 to run a 12" dual 4ohm sub in a custom vented enclosure designed specifically for that sub. the amp is rated 400rms at 4 ohm load and 600rms at 2ohm load... I was originally running a dual 2ohm identical sub before the Alpine dealer got a shipment of their new subs, so I could exchange it to a dual 4ohm and run it at 600 whatts rms. I have the new Alpine Type-R thats rated 1500 max and 500 rms.

When I ran the amp at 4 ohm load I was putting out 0.2 volts to try to get the full 400 whatts, because running it at 4 volts like the deck shows for its preouts sounded really weak. I enjoy having the quality aswell as the power and deep thumps in my car. Everything worked fine and I was happy overall with the performance and SQ and couldn't wait to get my new sub so I could run it at 500rms and feel the difference. Even when I had the amp turned up all the way I didn't have to worry about melting my voice coils on the sub because it was pretty much dummy proof for people that don't know how to set their gains and besides having it set to full would only be putting out 400 whatts rms and my sub was able to handle 500rms without any problems... I noticed at 0.2 volts at almost full volume I was getting the deepest cleanest bass without clipping. the amp however got pretty hot but I don't know what the max temperature rating for it is... the dealer told me it would go into safe mode at around 170 degrees F (so he thinks), and I've never seen it go over 150.

Everything was fine until my new sub came in... The Alpine dealer swapped the old with the new and I was now running 600 whatts rms.. the dealer told me to set the gain on the amp to 4.0 v like the deck shows... I did that and it sounded weak so I turned it up to 2.5 v and 1 day later to 1.0 v... and I couldn't believe how loud and clean it sounded... I was afraid to turn it up more because I was afraid i'd go over the 500rms rated for the sub with all my eq's set high on the deck ... after a whole day bumping passed by... the next day when I was driving around bumping I noticed the sub get weaker.. and then an electrical smell was coming from my trunk with the seats down... I brought it back and reset the gain to 4.0 v so they wouldn't get wized... obviously he knew I turned it up tho. but he was still kind enough to replace my sub (he told me the coil was in the process of getting completely fried) before when he told me to set it to 4.0 v he said to break in the sub first so not to play it loud at first... I did that before turning it up.

Now to my questions.... Is there a specific time it takes to break in a sub...? I heard from my buddy who has a JL dub7 that I should let my sub break in for a month or two before I turn the amp up a notch.. and another month before I turn it up another notch...  He's running 1000whatts rms.. into a sub thats meant to handle 750rms.. he's also got the amp turned up 3/4 to try to match his sub rating and it sounds awesome... he's never had problems with frying a coil... What do I do? I want the power I've had, before I fried my coil on the sub and had to exchange it... I don't want to fry the coil again... I agreed to have the dealer set my gain and eq's... the guy that set it left the amp gain at 4.0 to match the deck and he switched my eqs on my interiors  through my head unit which wized me off cuz it sounded like crap so I set those back to the way they were... and I left the amp at 4.0 v.  now it sounds good... but its not powerful at all like it was.. I'm afraid to turn it up because I don't want to have to go back there again to tell them I fried another one of their subs haha. Can anyone give me some advice on what I should do?

he said to break in the sub first so not to play it loud at first... I did that before turning it up.

Now to my questions.... Is there a specific time it takes to break in a sub...?

Answer:  when you're sure the system is set up 100% correctly.  You fried voice coils because of improper and inaccurate setup.  Look through past threads on this forum for subjects dealing with setting gain. 

Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Turn the gain back down. This is a simple problem. Your expectations of bass output is greater than the capabilites of your system. Without turning the gain back down, you will indeed fry another coil. What cd player are you using. It sounds like an Alpine with a really weak preout. I would look at a line driver or  a Eclipse 5 volt cd player to try on the system first. Then if that is still not enough, the only option left for you is another sub and a larger amp.

the deck im running is an alpine cda-9855 glide touch: I guess it sounds alright but I don't feel the deep bass that felt good when I had the amp turned up to 1.0v ... and I don't get how my friend has his turned up 3/4 of 1000rms. running the same exact head unit as mine... and his coil on the sub never fried?.... why can;t I turn it up more than 4.0v if he can?