McIntosh users.. What is the difference between the c47 and c48 preamps?

Both units have very similar specs and look almost identical. What is the difference? 
The c47 looks like a current model and the higher number c48 looks obsolete.
The C48 was recently discontinued.  C47 has a more fully featured DAC with DSD and DXD capability where the C48 "only" offered up to 32 bit 192 kHz PCM.  Both support MC and MM phono inputs.  It really all depends on whether you need the fancier DAC or tone control more.

Hope this helps.  Happy listening!