Yes, good advice to stay away from those.
I guess I would also say, for simplicities sake, to try out integrated amps as much as possible - things are more straightforward there as no need for a preamp. One requisite is that they need to have very fine volume control ideally.
Is the cable you got from preproman an adapter for the regular HE-6 cable? If so, best practice is to connect it to the amp, zero the amp volume, turn the amp on, and then connect the headphones and cautiously increase volume. That way the headphone is not exposed to the power-on "thud" that some amps exhibit (these should, I hope, be relatively few and far between, but better safe than sorry). Check and double check to make sure the adapters banana plugs are definitely connected to the correct channel and polarity, incorrect connection is another good way to fry your headphones. If you do these simple steps everything should be just fine. I've used my HE-6 with Merak monoblocks at 200W/channel and had no issues as the Auralic Taurus Pre was the volume control, so very nice volume control.