Thank YousA big thanks to Pete Millett for lugging this amp all the way from US for us here in Japan and a further added thanks to Amos/Currawong for shipping it to me from his hometown down south, to me in Tokyo to have an opportunity to listen and review this amp.
Apex Hifi and Pete Millett are names that is well known to the veterans of personal audio. Pete doesn't churn out new amps the way Toyota would revise their Prius, however what he does produce are solid proven products such as the Pinnacle and Teton, and most recently he's leveraged some new technologies in his latest Sangaku amp.
The Sangaku uses the Nutube tube package which employs vacuum fluorescent display technology from Noritake Itron Corp. The package which looks similar to an IC chip with pin outs and glows blue/green fluorescent light when powered on. It's even microphonic like regular tubes. However it seems it doesn't require a long warm up time like regular vacuum tubes.
The amp is a very compact 22.3cm x 23 cm x 5.5 cm designed to be laid flat. Due to the front panel, can't be laid on the side (for those seeking to save space). Pete went for a basic amp only design leaving the user to have the flexibility to use the DAC of his/her preference. The amp is versatile in accepting 1x XLR pair for balanced, and 2x RCA pairs for unbalanced. It has also a pre-amp out at the back, and unbalanced 6.3mm and XLR 4 pin balanced out socket in the front. The input and output selector switches are push buttons that just rotate around the various options. For the 6.3mm single ended and XLR 4 pin balanced out the output selector further provides a low and high gain option.
The volume knob is also smooth with no perceivable channel imbalance.
As earlier indicated in the introduction, the Nutube is sensitive to vibrations like normal tubes. The way the Nutubes are mounted on the PCB and in turn mounted within the chassis, any vibrations on the Sangaku amp would cause the Nutubes to ping. This include whilst plugging in the headphone into the socket, pressing the input/output selector buttons, and in general tapping on the chassis. The good news is that the microphonic ping from the Nature doesn’t ring for long - light taps would settle in about 3-4 sec but a bigger tap would take longer for the ringing to settle. Some sort of dampener on the soles of the amp would help.
Unlike other tube amps, the Sangaku and Nature produces little heat. I can’t count the number of times I’ve burnt my forearms accidentally touching my Zana Deux tubes whilst reaching to the side/back to power it off on or to fiddle with the cords behind. The Sangaku is vented however little heat is produced from within.
SonicsMy setup is Audirvana Plus 2.6.4 on my iMac to the iFI Micro iUSB 3.0, Invicta 1.0 to the Eddie Current Zana Deux pre-amp out into the Apex Hifi Sangaku (Single Ended connections all the way through). The headphone used is the Focal Utopia cabled with Moon Audio’s Silver Dragon.
The Sangaku is mostly a transparent amp. It doesn’t add colour to the overall signature so having a good source helps. The amp has has a more distinctive left/right separation than my Zana Deux (ZD), but the overall tonal signature doesn’t seem to be as full bodied as the Zana Deux. That’s not to say my ZD is bassy but the the ZD seems to have a bit more “weight” to the signature making the ZD a little more holographic and with a little more 3D imaging than the Sangaku.
However the Sangaku having the distinctive separation gives a (soundstage) wider presentation than the ZD.
The overall signature difference between the Sangaku and Woo Audio WA8 is greater than with the ZD. The WA8 has a noticeably warmer signature than the Sangaku, making the Sangaku sound “light on the feet” by comparison.
Tonal signature and sonic presentation-wise, there is little to fault with the Sangaku. Compared with the Zana Deux and WA8, it’s merely preference of tonal signature and synergy in pairing. For example, with my personal preference, I’m happy with the Utopia with stock pads and the WA8 as the Sangaku is a little too “light” tonally for my preference. However, I believe my opinion would change if I had the Elear pads on my Utopia with the Sangaku- of which I could perceive that to be a decent match. Unfortunately I’ve sold my other dynamic driver headphones.
My minor issues with the Sangaku is more related to the microphonic nature of the amp. I’m more conscious of how I plug in my headphone into the socket, vibrations from its surrounding on the table, etc.
However I appreciate its size - a seriously compact tube amp that packs a punch in sound.