nakamichi vs threshold

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.

Thanks for the answers.
Tonykay, what do you think about the differences between PA5 and PA7?
I am asking myself : Maybe PA7 is a bit over dimensionned for me, too much heat, too much weight... ?
Will the additional power improve the sound on JBL L112 ? (89db efficiency)
My listening room leasures 25 square meters.

I've heard a good number of technicians comment about that design- as I understand it, it is one of Nelson's earlier designs but due to construction or other factors did indeed have a reputation in the service industry (I ran a service shop for 15 years before going into the manufacturing sector) for stability issues.

These days if one has survived I would expect that filter caps should also be serviced out, but there are a lot of amps that are more deserving.

A buddy of mine had the PA-5 I think it was. Great sounding amp. I remarked over and over how good I thought the amp was. If it had reliability issues I know for a fact he never would have purchased it.

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.