Here's the situation: small 100wx1 amp going under the passenger or driver seat. It will be used probably for a tiny sub to give the midrange a little 'oomph'.

I'm quite well versed in the whole deal and do agree that the ideal thing would be to run a cable from the battery, but the voice of reasonability tell me that even a 10amp feed would be enough since it would hardly be ever turned up. Plus no mess with holes or taking too much apart.

Here's the question: what would be a good place around the dash area to get a constant 12v? (amp will turn on from remote coming off the headunit)

 

I know its a PIA, but you should still go to the battery for even a small amp. Everything will suffer if you take a shortcut like that (possible damage to under dash wiring, amp will get starved for not enough current, etc.)

I had a 45x2 amp that I was running in trimode on my wifes old Tercel (years ago). I was able to push a set of Boston components up front and a 12" RF sub in an infinite baffle set up. I sounded remarkable good and got some good volume!! I had 8ga straight from the battery for it.

 

'Overcompulsiveness' took over so ran an 8 gauge from the battery for a total cost of ~$5

Good thing that same point after the fuse can be used for lights and anything else. (PepBoys fuse)

 

RUN CABLE FROM BATTERY!!

it may seam that it doesnt pull much power, but it will

 

Go to a local stereo shop and buy a 100 or 200 watt Amp wiring kit. It should cost no more than $30. Run the wire directly from the battery. Everything you need will be included: 8 guage power and ground wire, a fuse holder, 30 amp fuse, a grommet for the power wire, O-rings for power and ground, heat shrink, zip ties and split loom to clean it up.
Don't take shortcuts, you will pay the price later. E mail me if you want a list of tools you need to do the job right. That way, you can add a bigger amp in the future easily.

-Nick