I never heard Nirvana Plus and I'm so happy with my beautiful GK-1 and AKSA55 that I don't believe an amplifier can sound better, but with Hugh and his team all is possible.
Pabiz,
Let me put it this way ... and here I'm making an assumption based on probability so please forgive me if I have made the wrong assumption.
You are Italian, therefore you are Catholic. Like many other religions, Catholicism requires you to "have faith" ... no-one has actually seen any of the miracles described in the Bible but we believe they happened - ie. we have faith.
So it is with the AKSA, AKSAN and AKSAN+. Each of these steps improves the base product. For instance, the amount of extra base which comes from an N+ is astonishing.
Very few people have actually directly compared a base AKSA with an AKSA N+ ... ie. swapping from one amp to the other in the same listening session. However, everyone who has done an upgrade (either from AKSA to AKSA N or from AKSA N to AKSA N+) has been delighted with the "new" amp they got as a result. They heard a difference from the upgrade and it made their amp sound even better!
You have to have faith, Pabiz. Hugh did not put these upgrade kits together as a cynical exercise to take more money from his customers. He was inspired to do a lot of experimenting as a result of the tweaking that various AKSA owners have reported on the Forum.
Yes, an AKSA 55 is a very good-sounding amplifier. However, if you upgrade it to a 55N+ it will deliver even more sonic beauty to your ears!
Remember, as they say in the classics "have Faith and the Force will be with you!".
Regards,
Andy