Are Nakamichi amps any good?

I currently have a Krell KST 100 amp with a YBA 2 preamp driving my Vandersteen 2's but Threshold amps have caught my attention.

1) Would a Threshold amp be a step up from the Krell?

2) Are Nakamichi amps any good or are they Threshold wannabes?

I'm trying to keep the upgrade below $1000 and I'll recap amp if needed.
Although both were designed by Nelson Pass, the Nakamichi amps are anything but Threshold wannabes. I can't say how much of an upgrade you can expect over the Krell (which is a very nice amp). You may be better off updating the Krell. If you buy a Nakamichi, you won't be disappointed! I was happy with my PA-7.
Nakamichi was very popular in the late 80's and early 90's.
They do make a good product, just not as popular any more.
I have one of the Nak stasis units and it is very nice despite being an older design now. Get one at a decent price and you can't go too wrong and should be able to resell for what you paid if you don't like it.
I would take an amp designed by Pass over a Krell. The Vandersteen's are very detailed speakers and your old Krell, while well made and very powerful, may not be the best match. I think you would be very happy with the upgrade.
The Nakamichi amps had a reputation in the service industry for being unstable and prone to failure. They were not popular on this account even back when they were being made. They sound OK, but they are not the sort of amp that you want to push hard or abuse.
Nakamichi amps NEVER had a "reputation" for being unstable. They were a Nelson Pass design and well-respected when introduced, and still popular today.
They made a PA-7 and a PA-7 MK-2. The MK-2 is a better amp but hard to come buy. If you can find one at a good price get It. they are hard to find in mint shape tho.
I had remembered minor problems with these units from my years in the business, went to my old Tech, he said that the Nak amps had protection circuits that were a bit touchy and all in the original PA 5/7 really need to be replaced, but the series II didn't have that problem... Also on the Original PA series, there were minor issues with bridge rectifiers. He said that they certainly had to deal with those problems, but overall a sweet design and very stable amp.
Well, that's 2 techs who say the Nakamichi amps had reliability problems. Whether that's touchy protection circuits or bad bridge rectifiers, minor or otherwise.

I think it's safe to say that TonyKay is wrong and that Nakamichi amplifiers (regardless of how splendid a designer Nelson Pass might be) had issues.
When you spend a lot of time reading this forum, and others on the internet, you hear about individual issues with every manufacturer. Does that mean that every component is flawed and should be avoided? Of course not. It's one thing to say that a design had issues, but to say that Nakamichi amplifiers "had a reputation for being unstable and prone to failure" is simply NOT true!
As I understand it, Nakamichi bought the licensing rights to the Stasis technology from Threshold, Nakimichi presented their version of Stasis amps to Nelson Pass, who briefly tweaked it, and then Nakamichi went on to manufacture it with Japanese parts and construction.
The pure Japanese Nakamichi 420 is a superb sounding little amp.Only 50 watts but high current.
Better sounding than the PA7E in my experience.
Nakamichi amplifiers don't need defending. They were highly praised when they were introduced and still well-respected today. Ask someone who really owns one. If you can find one that hasn't been abused, and is selling in your price range, grab it it with both hands. You won't be disappointed.