I keep reading great things about the NVX XPT100/HM5/Jaycar/FA-003, so I ordered a pair for my teenage son yesterday. He owns HFI-580 but has complained about dialogue clarity. I thought these should be a good complement to his Ultrasones. For the Sonic Electronix $80 price tag, doesn't seem like these can be beat for a good pair of closed headphones with a neutral signature.
Only, my son lives in a different state with his mom during the school year. I won't get to hear them until June
You made the right choice! However, you should really note that because of their neutrality and transparency, they're really revealing of the source. A good amp really makes a difference in order to really reap the benefits of their (imo) perfect design. They can of course be optimized with a few mods but as you said, certainly nothing competes even close at $80 for their true value.