I bought a Gustard P26 Class A preamp with rollable opamps out of curiosity and didn't expect much from the device. I've added it to my chain and to my surprise it made a sonic difference with the stock opamps. In this case with the Pontus II, it added brightness, clarity/resolution, instrument separation and sound stage (probably due to the brightness). The warmth seems to be push back a little bit and I'm guessing this perception is due to the added brightness. Furthermore, some have commented with the Burson V6 Vivid opamps, it kicked it up a notch. I have yet to do so, it'll be on the roadmap down the line. I've done my assessment with the FA-12 and LCD-X '21.
I was entertaining the idea of upgrading to the Venus but with the new addition I'm satisfied with the outcome and stay firm for now.