We came across an old Conrad Johnson tube phono stage and even in stock form it sounds really good. If you want the best sound you can from LP then you would be compromised to go with an all in one unit. We repair and modify components and even the old Counterpoint preamps that we upgrade are not as good as the CJ as a stand alone unit. The B&K is a basic good preamp but overall really nothing special. Same goes for the AI which is typically hard on tubes and as a preamp is bettered by the Prima Luna tube preamp linestage.
Happy Listening.