Upgrading preamp. Best for under $1K

Thanks for the responses! It seems tubes is the way to go for preamp but will it match well with the B&K amp?

It'll depend on the specifics, but should match up extremely well.  You can always experiment with brands and tube types to tailor the sound to your liking.

Tubes 4 Hifi has several excellent fully assembled tube preamps within budget: http://www.tubes4hifi.com/pre11.htm