If you want high quality then it is time to start looking at Audiophile Circuits League's modules. The Multi Function Discrete VCO that we looked at here is absolutely massive sounding... Which probably doesn't fully come across on YouTube however if you were there in the flesh you could really feel the ground move beneath you....
The Multi Function Discrete VCO really takes the idea of a sub oscillator section and runs with it... It gives you the exact same outputs as the standard oscillator but in the sub section.
In this video Stefan took us through the oscillator and mixed up some waves to show off the sound of this thing.
More info at ACL
Highly configurable Eurorack module