Various tube preamps (Rogue Audio 66 & Mag 99, Sonic Horizons, Hovland HP-100, Lamm LL2 (can't remember if it was a deluxe but was my favorite of all of them) L2-Ref, ARC LS-26 & Ref 3). I am sure I've left a few off that had extended audition times in my rig.
I've also had a Bryston .5B (first preamp mated to a pre-NRB series 3B amp - my first really decent setup), BP-26 and BP-17 all of which did the job but I'm just someone who prefers tubes in the mix. All were married up to various amps of various generations of Bryston amps dating back to the late 80's though I have never owned a cubed version amp but apparently some do mate tube preamps to cubed amps...
There is no silver bullet so enjoy the ride - its your system, your ears & your wallet