"But am I defeating the purpose of the expensive pre by keeping halo?"
I understand why you would ask that question, and it certainly makes sense, but that type of thinking will hold you back. Its easy to go out and buy good components, and get good results. If you want a system that competes with some of the best sound availiable, then you need to build a systen, not buy good components. System matching is the most important skill you can have in audio. Not only will you get better sound, you'll spend a lot less money in the process. Instead of asking yourself if it makes sense to spend the extra money on an expensive preamp, ask yourself if the preamp has the qualities you think are important. Then you need to consider how it will match with the rest of your other components. Don't worry so much about how much it costs, because if you know what you're doing, you'll be able to find a solution.