I do not use headphones, so if I buy this DAC, it would be integrated into my existing stereo system.  The signal chain would be:  Bluesound Node 2i streamer, digital coaxial cable, RME ADI-2 DAC FS, Parasound P6 Preamp, Parasound A21+ Amp, Speakers.  Can this unit be used in DAC-only mode?  If I can process the signal through my existing preamp and amp with no problem, are the bass, treble and equalization features of the ADI-2 DAC FS still usable and available?