Am input impedence of at least 47K, 100K would probably be better. If I had to select a SS power amp with 47k imput impedence and high current enuf to drive 4ohm (and lower) impedence loads well, in your price range, I would find a used Muse 100. The combo of the Muse and the MFA should give you some warmth yet retain good drive as well.
Hope that helps......
Hope that helps......