Got this a few days ago and had the chance to compare my (not burned-in) unit with a Centrance HiFi-M8 using my Ipod Classic 160GB as a source (digital line out to each device's DAC section), and using my ZMF V1's (Fostex T50RP mod). I used high gain on both amps and the medium impedence setting on the HiFi-M8. Tone controls were turned off on the HiFi-M8.
The HiFi-M8 is more neutral overall, and has slightly better resolution and a slightly larger soundstage. Next to the HiFi-M8, the HA-P50's bass feels a little emphasized and bloated, and bleeds into the mids very slightly.
While the HiFi-M8 was indeed better to my ears, the TEAC HA-P50 sounds pretty darn good less than half the price. The TEAC's strong bass response is actually a good thing for me (provides that slam when I listen to certain bass-heavy genres), though I can see how it might very slightly annoy a neutrality-head. The HA-P50 produces a clean, lean, and spacious, sound overall, with a slight bass emphasis.
Hope these impressions help anyone considering this product!