Preamp for Kr Audio Kronzilla SXI


I have a Kr Audio Kronzilla SXI integrated amplifier, which uses a passive preamp stage that is basically a volume control and switches for inputs. While I've been very happy with this amp, I'm wondering what kind of improvement I might get if I added a nice tube preamp to my system and bypass the passive stage.

I'm interested in preamps up to $3000 new or used. Some that I was curious about are the Dodd battery-powered preamp, DeHavilland Ultraverve, CAT SL-1 Mk3, Lamm LL2,Lector Zoe, but really just getting my feet wet.

Any advice would be appreciated. thanks.
hchilcoat
i HAVE A LAMM LL2 DELUX FOR FIVE YEARS WITH NO MODDS
AND STOCK TUBES. tHIS IS ONE OF THE BEST PRE'S ON THE MARKET. TIGHT BASS AND 3D CRYSTAL CLEAR MIDS
VAC Standard Signature is nice