I'm listening to the TH 900s through the HA-1 right now (via an iMac + iTunes + BitPerfect through USB).  It's phenomenal.  The HA-1 works just as advertised, including the remote control App.  Flawless (so far).

    Thanks for the feedback on this.  The following review was also very complimentary: http://headfonics.com/2014/07/the-ha-1-headphone-dacamp-by-oppo/2/   "The Lawton Denon D7000 also paired incredibly well with the HA-1, these are two headphones never to skip over if you own the HA-1"...

I'm also looking at the HA-1 for the TH-900's.  I'm concerned that the (nominal) 25 ohm impedance spec for the TH-900's falls below the recommended value of 30 ohm for the HA-1.  I read in a Benchmark article that running below the spec can possible degrade the performance of the amp or even...