An update on my HDP experiences so far (these comments are adapted from several posts over on head-fi.org, where there is a long thread about the HDP in the Dedicated Source Components section).
Since posting earlier, I got my DVD player out of the closet again and tried both the optical and coax inputs. And they both worked! I connected the optical to my Mac, it worked too. Both analog inputs work correctly (I had tested only the RCA analog previously).
What a pleasant, if puzzling, surprise. Somehow, everything now appears to be working correctly, including the optical input--for the last several days, anyways.
I now have maybe 40-50 hours listening to the HDP, and the smile on my face is making my jaw ache. This thing sounds fantastic. I haven't compared it to a wide range of competing products, but it clearly blew my old DAC (a SuperPro 707) away from the first moments I heard it. The difference between the HDP and the 707 is almost as dramatic as the difference between the 707 and my computer's builtin audio. The HDP is being driven by a iMac listening to lossless ripped CDs.
I have also compared the HDP with my trusty Creek OBH-11, and while the Creek has a lot more raw power, the HDP sounds better all around, clearer and more transparent sounding. It's not a huge difference, but it is noticeable. My earphone listening has been through Grado SR-125's and Sony MDR-V6's, both of which are longtime favorite phones. With the HDP, the Grado's sound fantastic, while the HDP starts to illuminate the shortcomings of the V6's. With both sets of phones, I do have to crank up the volume fairly high (around 1/2 volume), but as I said, I'm comparing this to the Creek, which I can never turn up past about 1/3 volume.
I've also been listening to the HDP through a Parasound Zamp driving a Polk RM3000 speaker system (two satellites, passive subwoofer) in my home office. It also has noticeably improved the sound of that system, especially when I crank up the volume a bit (i.e. when the wife is out of the house...) Although I do love these old speakers--their mid and high end is fantastic--the HDP also begins to reveal their shortcomings. By the way, the Zamp works great with the HDP because you can configure the Zamp to put itself into standby mode whenever there has been no audio signal for ten minutes. I can just turn off my HDP using the volume control switch and the Zamp, which is tucked back behind the computer, will power down after ten minutes. Actually, it's not even necessary to turn off the HDP; if I just stop or pause iTunes, the Zamp will power down. Turning the HDP on or hitting play in iTunes instantly powers up the Zamp.
Although I'm not convinced break-in is an actual phenomenon for a solid state device like the HDP, I certainly experienced what would seem to be break-in changes over my time so far. For a while, I was convinced the HDP was severely rolling off the bass response to the point I thought I was going to return it for a refund; I couldn't get any deep bass through either the speakers or headphones. Now as I sit here listening to Leonard Cohen (with my wife out of the house...), the bass response is as full and rich as I could hope.
I bought the HDP for its simplicity and audio quality (although the latter was not known beforehand, NuForce's reputation was a good indicator of what to expect). Using this in a home office setup, I like the small form factor of the HDP; it sits in its stand next to my computer, taking up almost no desk space. I can keep the amplifier tucked out of the way yet have the volume and headphone jack at my fingertips. While waiting for the HDP to ship, I was seriously tempted to get a Peachtree Nova, but really wanted a small footprint on my desk (in many home office setups, inches matter). So far, I'm really pleased with the HDP, and am glad I waited. NuForce has a new customer.
