- Written by Chris Heinonen
- Published on 10 June 2010
Since the AKG K701 headphones are notoriously hard to drive and really need a powerful headphone amp to bring out the bass, the first track I queued up for listening was Teardrop from Massive Attack's Mezzanine album.
It took no time at all to hear the difference that a more powerful headphone amp could make. While bass was certainly deeper and tighter than before, and far more present, there was as much difference in the rest of the music as well. Before when the standard Icon would try to hit those deep bass notes, they would come out a bit bloated and muddy, and the midrange and treble would suffer as well since the amp had no power left for them. Now those higher notes were coming through with far more clarity, letting me hear how they wanted the music mix to sound.
To make sure I wasn't just hearing the benefit of the DAC, I used the analog outputs from my laptop to both the Icon and the Icon HDP. The HDP brought out far more detail with my AKG's than the standard Icon did. I switched in my Grado SR60 headphones and the difference was much smaller between the two, as the Grado is a much easier headphone to drive that doesn't need a dedicated amp as much as the AKG's do. However, if you have a higher end set of headphones that can benefit from a headphone amp, the HDP did a good job of driving even a difficult pair. The improved USB connectivity in the HDP meant that I could try playing higher bit rate audio files from my PC that the Icon didn't support. For some direct comparisons, I used stereo DVD-Audio rips to compare to the standard CD versions. Comparing albums from The Flaming Lips (The Soft Bulletin, Yoshimi Battles the Pink Robots) and REM (Automatic for the People), the DVD-A versions had an advantage over their CD counterparts. It wasn't an advantage that was light years ahead, but it was there when I listened. Now that companies like HD Tracks and Linn Records offer 24/96 downloads, the ability for a USB DAC to support at least that resolution will become more and more important.
As NuForce said the HDP uses the same DAC as their high end CD player, I felt that I should try out the HDP in my home system and see how it compares to my usual CD players. The first comparison was to the Oppo BDP-83 using analog outputs. I fed the HDP using the coaxial output from the Oppo, and as they each used a different input on the NAD receiver it was easy to switch between them.
When I listened to Norah Jones' first album, Come Away With Me, the HDP seemed to offer a bit more detail and clarity in comparison to the Oppo. Jones's voice was the slightest bit raspy at times on the Oppo, but sounded much smoother and clear when played through the HDP. Additionally, the sound of a cymbal seemed to be a bit more natural and clear on the HDP. They were once again small differences, but each time my wife and I would listen (and the other person would control the NAD so you wouldn't know which component you were listening to) we would pick out the HDP over the Oppo. Given the high praise that is offered to the analog section of the Oppo for it's price range, the HDP did a fantastic job as a DAC in this case.
Against my Sony SACD changer, it was even easier. Natalie Merchant's Tigerlily album (MFSL remaster) and Beck's Sea Change (MFSL remaster) both are fantastically mastered albums, and both were made to sound even better when played back through the HDP versus the SACD changer. We use the SACD changer over the Oppo for the convenience factor, and because it still sounds very good, but listening to it though the HDP let me hear how technology had advanced in the past 8 years, with a larger soundstage, far better separation of instruments, and far more detail coming through the NuForce when stacked up head to head. That said, the killer use for the HDP as a DAC in a system came with the Squeezebox Touch. With access to my entire audio library, including 24/96 tracks, and the ability to use the HDP as my DAC, for $750 I had a system that sounded better than any transport I had heard in the price range, and I no longer had to deal with physical media at all. I didn't compare the analog outputs from the Touch as it had just arrived and I wasn't familiar with it's sound, but as a tiny, two piece transport and DAC setup feeding my main system, it was great to sit back, relax, and listen to anything I wanted to without ever having to get up from the couch.
The only issues I really ran into with the HDP is when I tried to feed it two digital signals (from the Touch and the Oppo) at the same time. Even if I tried to keep them both powered off when not in use, it seemed that sometimes the HDP would still be getting a signal from one of them, and so the other would not play when I powered it up, as there is only a single input choice for Digital on the front panel. For this reason I probably would not try to use the HDP in a system where I wanted to feed it with both the coaxial and optical inputs at the same time, but it was quite happy in a setup where being fed USB, analog, and one digital signal at once. Also, some files that I had on my PC were 24 bit, 88.2 kHz sample rates, and the USB input did not support that 88.2 rate. The ways around this were to resample everything up to 96 kHz in Foobar, or to send it over Optical or Coaxial instead, which supports that sample rate.