I am looking at the RAAL SR1a as a second headphone. It is supposed to be unlike any other headphone in that they are closer to sounding like speakers. This headphone cannot be driven by regular headphone amps. There are 2 specific headphone amps that can drive them, 1 by Schitt and the other by RAAL.
RAAL also provides a INTERFACE TO AMPLIFIER box that can be used to hook up a 2 channel amp to use as the headphone amp. I got interested in this headphone because of this 2 channel amp support and also the fact that the SR1a was designed using the Benchmark AHB2. I own 2 of these amps and it could be an ideal match. The USA distributer (or owner) is local to me so I will try for a demo after COVID. Low priority though.
My dealer told me that the Hifiman Susvara and Meze Empy are the 2 he owns and have some similarities. I own the Meze and love it with the WyWire Platinum XLR (much better than stock).