Creating a topic thread for this Headphone Amp.
Have one arriving tomorrow, so will post some photos of the actual unit then.
To be used with Dan Clark Aeon2 Noire planar magnetics and a SkyAudio custom dual mono silver cable, posted here Cables - 3rd Party/Upgrades & Recommendations - #483 by simes_pep
Will replace a Burson Soloist SL
Source is still Naim NDS with 555DR on the digital circuits and Sean Jacobs CHC DR3 on the analogue circuits, in a Roon environment, connected through a Sim Audio Amp Tape-Out.
I also have a Bakoon EQA-11R Phono stage, which has the Stari link current outputs, so should be able to use these directly with the current inputs on the HPA-21
Of course, Enleum has been launching it newer HPA-23RM, with circuitry common to the HPA-21 and the AMP-23R
Actual images of the unit
Then replacing the Soloist SL next to the Dan Clark Aeon2 Noire headphone on their stand
And listening impressions, of the HPA-21 on the Current output
Very quiet, with very black background
Sweeter in the treble, some of slam & punch of the Burson gone, but replaced by a refined musicality in its presentation. Soundstage is just as detailed, but an additional air to the picture.
Well worthy of the past reviews, able to be found on this amp.
Now let see if I can drain the battery in a listening session!
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Update
I have now connected up the Bakoon EQA-11R current output to the HPA-21 current input, the “Satri-Link connection” using a pair of BNC/RCA with a BNC adaptors (trying to find out what the original BNC/BNC cables were & whether still available), and WOW the presentation over this connection, makes the RCA connection through the Sim Audio Moon Pre-Amp sound splashy and ill-defined, more detail with even less noise.
So the Satri-Link connection is Current amplification from the cartridge to the headphones, worth the time to make this additional connection.
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Have now completed an isolation platform for the HPA-21, as I noticed there are indentations in the base plate for a ball bearing isolation platform RCK-11 (now unavailable), but I imagine similar to the one for the EQA-11R phono stage, where there is an isolated base plate, siting on four ceramic ball bearings.
So I now have something similar for the HPA-12
Firstly a small marble plinth with a sorbothane sheet underneath to isolate from the other equipment.
Then 4 Titanium pucks, with 7/32 ceramic (Silicone Nitride Si3N4) ball bearings.
The ball bearings were left over from experimenting with changing the steel ones in my Michell Orbe turntable. I had the choice of the Silicone Nitride, Ceramic Oxide or Delrin, but since the Silicone Nitride was rejected in both the main bearing position (Cernamic oxide won there) and in the Suspension towers (Delrin won there), I used the Silicone Nitride, as there is no movement and the load handling is small spread over 4 contact points.
The pucks have a large indent in them, so that the ball bearing sits within and don’t roll off or away. The initially implementation of this, was with some spare Michell Audio Tenderfeet where the indent didn’t hold the ball bearing, and they were going off in every different direction, when trying to align 4 feet into the base indentations.
I believe this to be an optimal solution given the official RCK-11 is now unavailable.
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