Pirst Fost! Welcome!

FWIW, I had the same question when I tapped into the pretty-slender-looking harness connector leads on my WRX (I also have a separate HU, a Kenwood 6017). Anyhow, I haven't measured it scientifically, but the current draw of the Empeg (I know that it has been referenced on the BBS a zillion times) combined with the Kenwood doesn't create any strain. I'm using the factory fuse for the past 9 months and no problem. I just concentrated on a big-time direct cable to the amp in the boot/trunk (something like that -- it's a wagon/saloon).

If you search on "WRX", there's a link somewhere to pics of my install and the harness connections I made. I went a little overboard and am not advocating that anyone do it exactly the way I did it, but it may demonstrate the concept of creating a "Y" feeder from the constant positive, switched positive, earth/ground, and illumination from the (Metra? Scosche? I don't know) factory harness adapter plug that I got from Crutchfield.

Hope that helps!

Measure 6 times, cut once!