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.