So should stick with the HE-Adapter to prevent noise problems? The preamp definitely raised the noise floor, and I'm only 1 hour away from the background noise becoming audible even with the HE-Adapter. Also comparing with amps that gave 1W or less, like WA7, I could definitely tell there's an improvement in impact and body. Nothing sounds harsh or thin. So I'm certain I'm getting more power than 1W.
How are you calculating the power I'm getting into the HE-500? I checked back at the specs of the HE-Adapter and along with the 10 ohm parallel resistance, there is a 25 ohm series resistor. I could probably just remove that resistor if need be and solder a wire. The 10 ohm parallel with the HE-500's 38 ohms creates 7.9 ohms, which would mean 50W, with the HE-500 getting 10.42W. Not sure how to calculate it when there's a 25 ohm resistor in series thrown in there. If plugging the HE-500 directly into the MiniX without any resistors, what's the power it gets then? I don't think you can do a simple divide by a factor of the resistance, otherwise they would list 100W at 4 ohms, rather than 80W.