I emailed PS Audio to ask if my Quintet was okay, since the blue light was flickering irregularly. They sent me a replacement power module right away and for free, "just to be on the safe side." Can't beat that.
Not only are the Duet and Quintet discontinued, but a look through the PS Audio web site offers no replacements, or even replacements in development. Too bad, I love my Quintet and the value proposition it offers.