Just how many outlets do you need for your stereo?

You need as many outlets as are required to plug in all your gear.

Another question to consider is, how many amps are required to effectively power your gear?

Finally, does it really matter whether you plug digital gear into a different outlet from your  analog gear when both lines go back to the same place?  Some advocate running the entire system off of one line.  Is one 20 amp line enough, 30 amps? 

I have overkill.  Five dedicated circuits, why you may ask.  I had one dedicated outlet and wanted two more and just got carried away.  It was my first major project after I retired.  I was a Building Inspector so the skill set was there. 

@vegasears  Thanks for that, I had to chuckle: yep, I hear you.   If your are going to do it, why not overkill it and never but never have to do it again!  Gotta love that philosophy!

@mitch2 The only reason for having separate digital and analog receptacles is whether or not the receptacles are independently filtered.   Analog gear doesn't usually pollute the lines with noise but is rather susceptible to it while digital gear usually pollutes it quite well.   If the receptacles are independently filtered, then noise from digital gear won't get into the analog stuff.   If you have no filters, then you are right, it doesn't much matter.   Note that some analog gear now uses switch mode power supplies, so they have their own pollution issues to deal with and from a noise standpoint, are not exactly pure analog.

Also, in researching this a bit further, I noticed that the Pangea Audio line of AC receptacles do not have isolated grounds while the PS Audio receptacle is an isolated grounded unit.   A point to consider when buying one of these upscale receptacles.

Good point @spatialking. I use three separate 20A circuits (one for each monoblock and one for front end gear) and do maintain some level of filtering on the digital side, using an Isoclean unit.  However, the quote below from the VH Audio site indicates the filtering protects the gear from grunge on the mains, although I suspect the filtering will also protect analog from digital as long as the analog gear is not plugged into the same side of the filter as the digital gear:

For the perfectionist, the IsoClean 60A3 II is fitted with two ultra low impedance Audio Grade 60+60 AMP RF noise filters to attenuate noise and RF associated with city mains. The dual filters of the 60A3 are separate and independent of each other, in order to reduce interactions between your system's components.

@mitch2 The filter should protect equally well in both directions if it was designed to be symmetrical.  But even if it was not, it should give you some filter action.