Another cool way to double up on your plugins is a great way to get the commercial pop/rock vocal sound - using 2 compressors in series on a vocal track.
There are a few cool benefits to doing this, and with plugins that model harmonic saturation (which Softube does), you can place one in front of the other in order to get more or less of the saturation characteristics.
A Fast Compressor...
For example, what I usually do is to take a fast, flexible compressor like the FET Compressor, and place it first in the vocal chain. I set this compressor to have a fast attack and pretty fast release (although experimenting with the release can be beneficial) in order to catch the quick, extreme transients in the vocals like plosives or air bursts. Having a fast, to very fast, attack-capable compressor is a good idea here. I personally tend to like a bit of a cleaner compressor first, as it is mainly utilitarian in making sure the big peaks are tamed without coloring them too much.
...followed by a Slower Compressor
Then, I follow that with a second compressor to smooth out the overall volume, and my favorite by far for that is the Tube-Tech CL 1B Compressor. With a bit of a slower attack and release (to taste, of course) I get a consistent overall vocal level that works with the track, and can determine how much of the saturation/color characteristics I want on this one pretty easily, and apply the necessary make-up gain as needed.
By playing around with the balance between the first and second compressor, you will find a ton of possibilities that allow you to dial in the in-your-face vocal sound that you are looking for. So, don't be afraid to experiment with various compressors, and the order they go in - sometimes less isn't always more!