I'm using a Tortuga LDRxB-v2 with a Lampizator Golden Gate DAC. The LDRxB has three sets of balanced inputs and one set of single ended inputs. Outputs are two sets of balanced and one set of single ended. I'm driving a biamped system with a tube amp on top and a pair of Spectron monoblocks on the bass. I use a second Tortuga, the LDR1B to attenuate the feed to the bass amps to match the level of the midrange/treble amps.
I've not heard the Tortuga tube buffer, but unless you're using power amps that have extremely low input impedance, I don't see a need for it, but then again I've not heard the buffer. I've compared the LDRxB and LDR1B with several five figure preamps and it easily outperformed all of them.
The Tortugas don't sound like any passive that I've tried. They have all the dynamics you'd want. They're the only passive controller that I've heard that has deep, powerful, and articulated bass that I only previously found in active devices. The soundstage is very wide and deep. Finally, instruments have a very realistic palpability that, when mated with a top notch power amp will amaze you. My Tortuga also has several features that I would not now want to be without-- adjustable input impedance and absolute phase inversion control, both from the remote.
I would recommend that you spring for the wiring upgrade. Have I left out anything?