"...the HPA-3B @300 and 600 ohms has about double the power of the 789 which is why I think it's a great amp to have.@amirm I bought another one (my second) that had sparkos voltage regulators already installed. I think that was to allow certain oamps.
I did fit two opa1656's which were recommended to me by a TI engineer last year. It took a while but the sound grew on me. I have the 789 running alongside it and they are very close but the HPA-3B has a little body to it and sounds fuller. It's very marginal but might be something to do with class A vs A/B.
Admittedly I lean more to the Matrix over the 789 and it pairs excellently with my mdr-z7m2 which are also upgraded with lambskin. DBS tech talk reviewed my modded set.
It's also worth noting that while the 789 has 6 watts vs 3.8 the HPA-3B @300 and 600 ohms has about double the power of the 789 which is why I think it's a great amp to have.
I wish they would redo this amp with the 789 form factor or just re-release it as it probably didn't get the recognition it deserved.
To anyone who reads this If you ever get the chance to pick one up I highly recommend it.
@MatrixAudio I had one of these and sold it, managed to get another and love it. Amazing amplifier especially with opa1656 opamps.
I wish they would redo this amp with the 789 form factor or just re-release it as it probably didn't get the recognition it deserved."
I own this too, and absolutely agree with you on both counts. Truly a great amp, especially for High impedance Headphones. I briefly owned the Drop THX 789 and I have found it underwhelming, especially on High Z. It was quickly sold and I had no regrets.
Unfortunately, there is no sign from Matrix that they have any will to relaunch/redesign the HPA-3B...