nakamichi vs threshold

Buy the Nakamichi and you will never look back with disappointment.

Sorry to disagree, but Nakamichi amplifiers have not had a "reputation for being unstable." Do some research on the internet and I doubt that you will hear many negative comments from current or past Nakamichi owners. Nakamichi amps still sell for a high percentage of their original cost relative to their vintage. I just don't want the OP to take the above comment as the last word on Nak amps. They are a Nelson Pass design and still well-respected today.

I owned JBL Olympus speakers in the 70s and 80s but I'm not that familiar with the newer models. At 89db, you should not have any trouble driving them with either the
PA5 or PA7. As I'm sure you realize, the 5 is simply a junior version of the PA7. For the extra couple hundred dollars, I would get the PA7 so that you'll have enough power down the road if you should get any of the newer, power-hungry designs that are being offered today.