I went to the demo at Audio46. I was there about an hour and spent 30-40 minutes listening to the Solitaire P and a Hedd that they kindly made available, all powered through the T+A HA200.
They provided a source (I believe it was Astell & Kern) and a tidal account. I listened to some tracks/albums that I am familiar with -- Massive Attack, Burial, Feist, Lorde.
Here are a few impressions.
HA200
The HA200 is a big, bold, powerful amplifier. It exudes high end. It is really stunning looking in person. The amp on display was the brushed aluminium version (they also make black). The front screen in very sharp font displays the menu choices, sample rate and volume. The LED lights on the front panel are bright blue and indicate the source and output. There are two VU meters, one for each channel, which are visually pleasing. The buttons, connectors and volume knob had a quality look and feel to them. The volume knob turned with precision. The amp has three headphone outputs: 4.4mm balanced, XLR and unbalanced. I used the unbalanced and XLR. The amp was impressive looking and sounding.
Solitaire P
The Soliatire P has an elegant look and is very comfortable. Soundwise, the first thing that struck me about the Solitaire P was its defined low end and full mid bass. It hits pretty hard and is somewhat unexpected. The soundstage was not large (you seemed close to the music) but the voices and instruments had good spatial definition. The sound of the midrange was rich and harmonic, but there was a bit of boominess or bloom that detracted and created a slight imbalance. At the same time, the headphone certainty had ample and expressive detail. The treble had good tonal quality; there was no brightness. Overall, the headphone offered an involving experience with superb bass and sub-bass, but seemed to lack a bit of focus.
Heddphone
The Hedd is a large headphone but I did not find it uncomfortable. The bass on the Hedd was clean and natural sounding. The Hedd produced a nice bass response but some may find it lacking in impact. The mids were precise with good texture to instruments and the right amount of loudness to vocals. The detail retrieval was top notch and seemed comparable to other high-end headphones. The highs were extended and non fatiguing (no glare or brightness). The soundstage was wide and with the drivers far away from the ears gave a mini speaker-like presentation. This was certainly one of the most interesting features of the headphone. Overall, I was impressed with the Hedd. It had very good detail, a deep soundstage, and offered an immersive listening experience.
Comparison
The Hedd had about equal detail and precision but less low bass than the Solitaire P, both with respect to impact and overall bass response. The deep bass on the Solitaire P is definitely something to hear. The soundstage on the Hedd was larger (or deeper). Both headphones provided very good detail and resolution. On the whole, I preferred the Hedd but really liked the Soliataire P as well.
Thanks again to Audio46 for this enjoyable experience.