I've used my DT880 with numerous SS rigs, including some FiiO amps: E17, E12, E09K and a Matrix M Stage. The M Stage would be the best out of that bunch. Sure, they sound great, but not optimal.
The only time I have ever heard the DT880s really shine was with my La Figaro 336C tube amp (disclaimer: this is the only tube amp I have used with the DT880) and via the headphone jack on an Audiolab M-DAC.
Cool. Thanks for the input guys. Keep it coming!