how much does a deck draw when turned off

Ok so I built a garage stereo using car audio components. It consists of:

• 3 Computer power supplys
• 2 amps
• Alpine CDE-102 Deck
• One switch
• a Few LED's

Currently I have it all wired up so the switch shuts off everything. The problem with this is when I turn off the switch I loose all the presets. I came up with an idea to wire in a 12 volt AC adapter of a house hold item. It's 12 V 200 mA. I wired in two relays so when I shut off the switch it uses the AC adapter to hold the presets. My problem is it doesn't work when I turn off the switch I still loose presets.

• Is 200 ma enough to hold presets?
• Do I need to use a cap to cover for the momentary loss of power when the relays swap?

If the deck was built in the last 15 years or so. The Yellow wire is where it draws all of it's power from.  The red wire is simply a voltage sense wire that lets it know it is OK to turn on when voltage is present on the red wire.  All power drawn goes through the yellow wire, hence the 10 amp fuse in the path of the constant wire.  At rest the 200 mil should be plenty, it probably draws less than 5 milliamps.   You will have to try it without the cap and see if it keeps memory or not.  If it is losing memory, you may want to try a capacitor.  A relay switches fast enough that a 470 mic cap should do the trick.