1.I would contact Don Scott. He has some inexpensive tuners for sale that can be tweaked for your situation. He may also align your present set-up.
bdscott@nac.net
2. That being said, what I (and all engineers I have read)have found is that money spent on the optimum antenna for your situation is 10x more important than the money spent on a tuner. This is just good systems engineering, especially in marginal situations. If the Audio Prism is that much better (I don't know either unit, I use an outdoor unit) than what you have now it is cheap at the price. Obviously, if you don't get a clean strong signal in, a Sequerra is just a light show, n'est-ce pas?