I have an Equinox as well as a Solstice (preamp/mixer/blender) and the MamaBear (acoustic guitar "modeler"--but not a modeler like what you might think; it's quite different and unique). I use all three on bass...mostly on my piezo powered Godins (being semi-acoustic and all), but I have used the Equinox as well as the Solstice on my "conventional" basses as well.
As a stand alone preamp the Equinox is inscredible. Yes there is tone shaping galore, and it a true audiophile-quality unit. Dead silent and very professional (certainly fits into my domain as a session player!).
Yet, it is kinda bare bones as far as intos and outas go. It has no aux loop, tuner send or such. It does have a mighty fine balanced DI as well as TWO 1/4" outputs (one which could be used as a tuner send...and the notch filters as well as the parametric have seperate bypass switches...but no "mute".
It is for this reason I use it in tandem with the Solstice (anotherfine preamp for bass, BTW (I use the Equinox in the insert of one of the Solstice channels).
Exceptional build qualioty and sound...yes, Rick Turnerand Seymor Duncan Do have a bit of a pedigree when it comes to designing high-quality preamps and pickups!
BTW, I replaced a Demeter HBP1 with the Solstice/Equinox combo...and all my pedals and rack effects with the MamaBear (OK, I am still using, quite sparingly, a Demeter analog spring reverb...). The D-Tar stuff is quite top notch, and to my ears sounded even better than the Dem (albeit without the Dem's "tubey-ness---I had replaced the stock tube with a NOS Mullard ECC82).
Very cool indeed!
Max