A major reason I say that is what I would consider to be the AcousTech’s absurdly high 10,000 pf input capacitance in moving coil mode, together with its fixed 100 ohm load resistance (which I suspect is necessitated by the very high input capacitance). For further explanation see the post by Lyra cartridge designer Jonathan Carr (JCarr at Audiogon) dated 8-14-2010 in this thread. And keep in mind that he is referring to capacitances as low as tens of pf, not ten thousand.
My suspicion, btw, is that the reason such a high input capacitance value was used is that it is serving as an inexpensive way of avoiding what would otherwise be issues in the design.
You may want to consider the Herron VTPH-2, at $3650 new. If you research past threads here and elsewhere, you’ll find nearly unanimous glowing praise from all who own it or have heard it (including me), as well as for Keith Herron as a wonderful person to deal with. Some other owners have reported finding it to be competitive with $10K phono stages. It has only unbalanced inputs and outputs, but I don’t see that as being an issue with your BAT preamp.
Good luck. Regards,
-- Al