Preamp question

Hi, I just purchased used Bat vk-75se .My current preamp
is Cat-sl-1 mk111. I am considering selling my Cat preamp
and getting used Bat vk 52se preamp. I was told that this
preamp is much better than my Cat sl-1. Please advise me
so i dont make a costly mistake. I thank you in advace for your time.
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.