I currently have the SMSL SP400 (THX 888 headphone amp) paired with the Lynx Hilo DAC.
The Hilo's XLR output level is set to +24dBu (12.28V) and the SP400 is set on High Gain.
Eventhough the Hilo is old tech (Cirrus Logic CS4398 DACs), due to its +24dBu output, the clarity and dynamics I get in...