I got a set of HE6SE V2 from Adorama sale. Running it on a Yamaha A-1000 vintage amp that I bought from ebay on speaker taps. I am using this $8 adapter on Amazon:
https://www.amazon.com/Fancasee-Replacement-Connector-Headphone-Earphone/dp/B07Y8LNMM6/. Before hooking it up, I verified the amp has common ground between the channels using a multimeter. Two additional simple adapters were needed to connect to the stock 4pin XLR cable: 3.5mm to 1/4" TRS adapter, and the 1/4" TRS to 4pin XLR adapter that came with HE6SE. Eventually, I will build a 4 speaker wire to 4pin XLR adapter myself.
I also got a HE adapter from ebay, but decided to skip it in the setup, why waste energy generating heat on the resisters
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Currently feeding the amp from Topping E30 DAC, but I have a Holo Audio May KTE coming. Feel kind of weird jumping from $130 DAC to a $5000 DAC. If I can't hear much difference, then it will be confirmed that I have tin ears
The Yamaha A-1000 was supposed to be its TOFL amp in mid 80s. The unit I got was completely cleaned, it was spotless inside when I opened it up. I was a bit concerned that I might need to find a tech to re-cap it since it is 35 years old, but it sounds great as is. I am also using it to drive the Raal SR1A through its interface box, sounds great too.
I am relatively new to hifi/head-fi, and I haven't heard many systems to have points of reference, but they sound great to my ears.