My pair of 8323's arrived today (purchased at the sale price of $17.40)... unfortunately they were DOA. There was no sound from the driver in the right cup--tested with both cords. I twisted the cable around in the jack a bit and managed to get severely distorted audio.
[Edit: Based on reviews for the seemingly identical Kicker HP541 on Amazon.com, it seems the right ear cup has a tendency to lose it's connection to the signal (which enters at the left ear cup). It seems to be related to the internal connection at the sliding adjusters in the headband.]
I have requested a replacement pair (I like what I heard from the left driver). I'll be sure to let you guys know about my experience with customer service!
[Edit: Emails from Monoprice's returns department have been helpful, timely, and friendly (although it seems that English may not be their native language). They sent me a UPS Ground label to print, so the exchange won't cost me a thing. They also had the foresight to warn me that the headphones were out of stock (probably a result of the sale) and that it might take a few weeks to fill the replacement order. I've sent my defective headphones back, and am eagerly awaiting a functional pair of which I can share my impressions.]
I also received the 8320 IEMs today. I don't like in-ear headphones, but I couldn't resist having Monoprice throw a pair in the box along with the 8323s. They fit my ears perfectly, unlike similar models I have tried. I agree with the multitudes of positive reviews across the interwebs on these, they are a very good buy for seven bucks and change.