David have sent me their hybrid headphone amplifier PA10.1D for reviewing purpose. David told me that PA10.1D SE version (299USD) is not like their older version, the version that he sent to me is their latest and revised version.
What made PA10.1D really stood out from the crowd is really their hybrid design for the headphone amplifier, which is using a vacuum tube valve (12AU7 – For GE series. or 6Dj8/6922 – For PA10.1D SE).
David have told me that this is a revised version than the old PA-10, as he described in our email conversation, he said that PA10.1D that I am having now is a refined version than the older version, which you can read the differences here.
Adjusting the volume will cause noise, although this is not a big deal but is something that worth mentioned. You cannot use PA10.1D once you turned it on, you have to wait for about one minute to let the vacuum tube warming up, there is an audible distortion if tube has not been warmed up enough, something that is very common in amplifier that using vacuum tube, this is not a big deal.
As you can see from my picture, this is actually very handsome and nice looking, you can see the tube from the outside and change it directly.
PA10.1D will run hot while you are using it, not something special for a vacuum tube headphone amp though.
PA10.1D sounded like what I expected from a hybrid headphone amplifier but not what I wished. First of all, it shares same ‘sound breed’ of similar hybrid headphone amplifier, which is insanely fast and engaging.
Secondly, I noticed the sound is overally very spacious and flowing, in a good soundstage.
Thirdly, it is very powerful (although I don’t like the 3.5mm jack idea even most of the headphones have 3.5mm headphone jack). For powering up a Hifiman HE500, AKG Q701 and 300 Ohm German-Maestro GMP400, I do not even need to turn my volume knob more than 25-30%, and I have already got enough level of volume. However, if I turning the volume to higher level, distortion will be creeping in as well, however, it is when I set it higher than what I usually listened to.
The problem that I am always concerned is the not that weighty bass unless you crank up the volume, however it is not exceptional bad, it is just that this can be better. Sound signature is generally quite balanced, treble performance of PA10.1D is quite impressive, good extension and detailed, especially when I play the song sexual healing by Fourplay, bass might be too polite, and quite laid back for the bass, especially when you compare to the treble. I would say the bass is not weighty enough.
Vocal is not what I expected from a headphone amplifier that employing tube, it is not lush or warm enough. It is far from bad, but I have actually expected PA10.1D will have a lot more grip and texture in the vocal, in the end, it just came out that vocal is just another solidstate sound, and to be honest most of the solidstate headphone amplifier performed better in vocal than how PA10.1D did.
I am not saying that PA10.1D is a bad device, in fact, it sounded quite good in an opened up space which is very spacious, and good top end. However, for the retail price suggested, I doubt that this will be a good choice.
First of all, tube amp normally will not last forever, so after some hundreds/thousands hours of usage, you might have to change the tube valve inside, of coz, changed to a better tube valve will promise better audio quality, but why the hassle? Especially when I think PA10.1D does not have the lush, warm tone that a vacuum tube headphone amplifier should have, and what made tube valve so welcoming in audiophile crowd is the tonality, I can’t find the tone to be honest, so just like I said, why the hassle?
However, all of these are just my ears, maybe if you have the chance, go and try them yourself, who knows you will have different like?