- Written by John E. Johnson, Jr.
- Published on 15 May 2014
The OPPO HA-1 Headphone Amplifier In Use
My setup is shown below, with the HA-1 on an end table next to my easy chair. The PM-1's are sitting on top of the HA-1 (do not cover the grille at the front, as the heat generated by the Class A operation exits there). My iPod is next to the HA-1 and connected through the front USB port (asynchronous), labeled "Mobile" on the input menu.
Here are the menus selectable by the knob on the left of the HA-1.
First, the Inputs. Mobile is highlighted as the selection for use with my iPod. I didn't use the Bluetooth connection, since Bluetooth bitstreams are lossy, and I listen only to lossless encoded music. The Bluetooth connection would be OK for MP3's.
There are three additional screens to choose from. The first one, shown below, indicates the status, i.e., Source, Audio Format, Gain Level, and Volume.
You can also choose Spectrum, which shows the music playing at various frequencies.
The screen I like is this one, the VU meters. It shows the digitally recorded level of each channel. Rarely does it get close to 0 dB, which is the digital clipping level. Most of the time it stays around – 10 dB to -5 dB.
I played music, mostly classical, from my iPod and also from my computer, where I stored the downloaded DSD128 music files. All of it just sounded terrific! The highs were clean, and the bass was deep. No excessive sibilance or congestion in the midrange.
I think it's fortunate, at least to me, that I did not hear any difference between 24/192 and 24/352.8, because if there were a significant difference, it would mean I have to upgrade all my audio equipment that uses DACs (and that's a lot). For some of you though, I am sure you will jump in line to purchase 24/352.8 albums and get a DAC that will decode them. May the force be with you.
Note that the high resolution digital files that were downloaded from 2L are all based on DXD (Digital eXtreme Definition) masters. This format is 24/352.8 PCM. All of the music formats offered in their albums originate from the DXD masters, so even the DSD (Direct Stream Digital) albums originated in PCM. The reason for this is that the 1 bit nature of DSD renders it unsuitable for editing, so it has to be in PCM format in order to be editable. The only true DSD recordings are those that are recorded in DSD, not transcoded to PCM for editing (meaning basically that they are not edited), and released as DSD. I would like to see all DSD albums state whether they have been recorded in native DSD, and whether they have gone through a PCM transcoding for editing, or if they have always remained in the native DSD format.