Preamp question

You're comparing two excellent tube preamps, namely, the CAT, which probably brings 85% of what is possible for the technology, to the BAT, which probably brings 95% of what's possible (very rough estimates, of course). That said, consider the following: (i) the CAT has really high gain and can drive sensitive amps to full loudness by the "10:00 - 11:00 O'Clock" settings on its volume pot, giving little volume control (that's why I sold mine), so see how it works with your new BAT amp in this regard; (ii) the BAT could be expected to have excellent synergy with your BAT amps, and both are fully differential balanced; and (iii) the BAT is really dynamic, but is somewhat "dark" a la Lamm, and you really can't roll tubes with it. My guess is that it will sound better due to better synergy - it's up to you whether it's worth it.