The VKFX is a probably not so known but very powerful , we could say modular, multi fx. You have a wide palette of "classic" modules (preamp, amp, phaser, delay, overdrive, etc.) and they are modelled after very famous products of the past. The VKFX was born as the perfect friend for Scarbee's electric piano libraries, and if you do not have a Fender Twin or a Roland JC20 in your room or if you do not want to spend time with them, it's really the best option. But it can be really really useful also in other contexts, in general for warming up and give an "analog" feel to virtual instruments, synths, etc. I've met people that use it on every track, just to achieve that.
And being it a modular thing, you can use just the modules you need and put them in the order you need in the chain. Very low on CPU too, and that's a big plus for me! Fair price, especially if you think at all the money you need if you want to buy just two or three of the devices modelled in the VKFX! Recommended!