So my week with the LDR300x.v3 has come to an end. I was able to test it with both the Resistor and LDR volume controls and also tried it in Active and Passive modes. Additionally I was able to compare it to my LDR3.V25 w/ OLED Display, which was updated from the older V20 version.
Testing the LDR300x.V3 in Active vs. Passive mode showed obvious differences. In active mode, the soundstage was widest and also had more depth. Decays lasted longer, adding to the perception of realism. Dynamics were the most obvious change, much more powerful and quicker than in the passive mode. Initially, I was quite unimpressed by the passive mode, but then I remembered that I had not run the impedance calibration against my system. After calibration in passive mode I felt that the sound was greatly improved, but strong vocals or loud orchestral passages seemed to be a bit more compressed and veiled compared to active.
Truthfully I could not discern too much difference in sound quality between my LDR3.V25 and the LDR300x.V3 in passive mode. That makes me happy, as I'm going to need to use the LDR3.v25 in my main system while my main preamp is out of the system for repair. The height of the LDR300x.v3 is about 2/3 of the LDR3.v25, otherwise they are very similar in size. I/O for the two preamps is very similar, with the LDR3.v25 having an additional 12v trigger. The USB port for updates is a micro USB vs. the relatively obscure USB A to USB A cable the LDR3.v25 uses. The LDR300x.v3 uses pin connectors to tie the boards together, compared to the silver wiring between boards in the LDR3.v25. I prefer the pin connectors on the LDR300x.v3 as it makes it easier to work on the unit if necessary. And if I recall correctly, the LDR300x.v3 is also less expensive than the LDR3.v20 was.
Testing the LDR300x.v3 with the resistor based volume control was interesting. It definitely did not have the frequency extension of the LDR. Listening to Alison Krauss' and Robert Plant's "Polly Come Home" didn't let the very lowest bass frequencies (the ones you can feel) come through. Likewise the highest frequencies were slightly damped, but as a plus, the very slight glare that I experienced with the LDRs did not exist. Some people may like this sound more, I would definitely recommend trying both if you purchase this preamp.
I did not try the amp in passive/resistor mode and can't comment on that configuration.
I do truly feel that the Tortuga LDR 300x.v3 delivers well above it's price point and would probably suit many audiophile systems. Thanks Morten for letting your new child loose on the community. Its nice to see how you continually work to upgrade and make your products more affordable!