For the HE6SE, nearly all comments I read suggested using older "vintage" solid state amps; I don't recall suggestions of tube amps. Many are happy with the Emotiva BasX (with headphone full power jumper) / mini A-100; others say the Emotiva still doesn't have enough power punch (but no audio measurements to support the claim). {So appreciate the positive comments regarding the use of tube amp}
The HE-Adapter is no longer included with the HE6SEv2 headphones, but it can still be purchased from Hifiman through their direct store—$99 plus shipping. From pictures, the adapter included resistors. But all of the commenters on other forums say there is no value in purchasing the adapter (unless it came for free), and to instead just wire up an adapter cable with 4-pin XLR on one end and Speaker Terminals (e.g. banana plugs, spades, bare wire) on the other; and then directly connect to speaker outputs.
Actually, the HE-Adapter appears to be perenially "out of stock" on Hifimans store, and I ended up buying it from this UK Audio store:
HiFiMAN HE Adaptor - Analogue Seduction
The HE-Adapter is a nice professional metal boxed headphone adapter => speaker terminal -> XLR headphone connector. AFAIK the HE-Adapter was never included with the new Adorama HE6SE V2, but was included with the original HE-6 release because headphone amplifiers of the time didn't provide enough power. As Planars became more popular the industry began offering high power headphone amplifiers, and Hifiman themselves have come out with headphone amplifiers that can drive their high power demanding Planars.
The Emotiva BasX A-100 has been in my "cart" for quite a while now - over a year, but after hearing about the Hifiman Planar affinity for tube amplification, I lost interest in the A-100, and began looking for a good inexpensive Hybrid tube amplifier - a design that brings tube sound and solid-state output together to provide compatibility with Planars and Dynamic headphones with tube pre-amplification.
Here is some information posted on the Hifiman.com website related to the headphones and amp pairing:
Hifiman themselves offered the HE-6 with Hybrid / Tube Amps, followed by an unbalanced SS amp, "
The EF6 from Hifiman".
@edahl - Here is some HE-6 vs HE1000 user commentary on selecting an AMP / DAC: "
Headphones & portable audio - HIFIMAN.com"
Hifimans top headphone amp is a 300B tube amp:
SHANGRI-LA
Hifimans's "budget" Shangri-la is also a tube amp:
HIFIMAN SHANGRI-LA jr
Hifiman pairs their Susvara with a tube amp:
SUSVARA&EF1000
I started out with Planar headphones with a Sendyaudio Aiva Planar. I found the Planar sound on the Topping A90 wonderful in comparison to my dynamic headphones. Hearing reviewers and owners report a wider sound stage with better dynamics on a tube amplifier, with tubes selected for their own personal sound choice, also encouraged my interest in finding a nice inexpensive Tube / Hybrid amp.
My relatively recent purchase of the Xduoo TA-20 Balanced 12AU7 (pair) Hybrid amplifier provided a welcome surprise, I could hear what the Planar owners and reviewers were gushing about, the Sendyaudio Aiva planar and Sennheiser 598cs both benefited from a wider sound stage and more impactful dynamic sound with a tube hybrid headphone amplifier.
So I went on the search for a good deal on a Sennheiser HD600 series headphone and ended up ordering an HD660s from bhphoto.com, and while I was out there searching - during the Holiday sales - I found the Hifiman HE6SE V2 and Ananda also on sale for large discounts, and I picked those up too.
I've spent most of my time since then listening to music between the HE6SE V2 and the Ananda (what I am listening to right now), and early on going back and forth between the Topping A90 and Xduoo TA-20, and I soon found myself staying with the Xduoo TA-20 and the Planars for all of my listening.
