should I upgade my Nakamichi PA-5?

I have a pair Proac Tablette Reference 8 Signature with Sony 9000ES & Nakamichi PA-5 using in a small room. So far nothing wrong with them. I just wondering should I change to PA-5II or PA-7/7II? is there any improvment? and what kind? thanks.
you have a great system, and though you may may not feel its mandatory, try adding a nice preamp to the mix.
I have a Nakamichi PA-5II. I felt that it was an upgrade from the 5. I have used it to drive my Magnepan's but since I am selling them I may sell the Nakamichi. If you live near Seattle feel free to come and listen to it.
Thanks Jaybo. I used have CA-5 Pre-Amp with PA5. Just because digital input, I just bought this SONY 9000ES. Did I make a mistake??(I still have that CA5)

And Thanks Bachtovinyl. I wish I clound come over and listen to your Magnepan. But I live in So. California.
i understand the sony 'may' sound fine without the pre. it would be interesting to find out how the sound changes with the pre in the system.....the sony is quite good.
I am sorry something missed there. What I have are Sony TA-E9000ES AV Control Amp (Pre Amp.) and Nakamichi PA-5 Amp. now
you should be good as gold then.