Two preamps are available....

The "factory refurbished" really doesn’t mean anything. They usually just do a full test and don’t repair anything.

Sorry, that’s not entirely true. It depends on the manufacturer and what was originally wrong with the unit. I sold hundreds of B-Stock units and had just as much success with these as any new units. I have also owned quite a few refurbs and never had a problem.

Buy the refurb...

@gerryn...if it's a McIntosh, then rest assured it was completely gone through and made like new.  McIntosh is a very obsessive company when it comes to their products.  One of the best out there as a matter of fact.

Sorry, but I'm going to jump in here again.  I was in the high-end audio business for over 25 years.  Not once did I ever send a "demo" unit back to the manufacturer, (unless there was an upgrade to the model).  We always sold our demo units at a discount.

I would be more worried, (if I was to worry over such a thing) that the used unit might have been a dealer demo.

Also, as good as NAD is, it's not a McIntosh.

Again, buy the refurb and don't worry, be happy :-)