I have a Kenwood 50x4 head unit, and recently it has been more flaky about cutting off and rebooting if i turn the volume up very loud. I finally figured out why, it wasn't getting enough current out of the stock radio power wire. It is definitely a pretty small wire, so I'm not totally surprised. I wound up running a new wire straight to the battery, and now it works fine. I did check resistance of all my speakers, from the plug at the head unit, and they were all right at 5 ohms, so I know they're not shorted. Anyone else ever have to do this, or could it just be a bad connection on the stock power wire somewhere?

I'm thinking that it could have been a bad power wire connection.When the connection temporarily 'disconnected', that's when your head unit would go bonkers.Just a hypothesis here (I learned that word in 8th grade science lol.)I had a similar problem with 2 head units I installed,until I replaced the main power wire like you did. Now all systems are go....

I thought about that, but the cut-outs happen when a loud music part plays, like a bass kick or something. It's not related to movement or vibration, it would even do it sitting still with the engine off. I thought about maybe a bad ground too, but the head unit ground wire reads 1ohm resistance to the car body, which I assume is fine. The stock power wire does seem awfully small though, I swear the wires were heavier gauge in my old 83. I'm wondering if it's because my car came with the premium sound thing, where an amp was powering the rear speakers, and not the HU.

The stock wire size is fine. There is a bad (high resistance) connection. The HU pulls more current as the output level goes up. The more current it pulls the more voltage drop at the high resisantce connection there is. Until the voltage at the HU drops to the point it shuts off. You should move your HU ground to the chassis too.

i had to do it... my power wire wasnt sending any current for some reason or another....pretty simple, i just added a 30 amp fuse on the line just to be safe