I try to use presets as a guide rather than a default state of things. Anyway on my Soundcloud page I have two identical songs (well nearly). Master 2 is my updated mix of the same song. I was aiming for better dynamics so changing the arrangement and track volumes all helped me get a more balanced sound.
 
I know some EDM is all punch and no dynamics virtually. Further limited and reduced by online streaming services.  Which is good, so the sound is not compromised by the reduction in bandwidth or algorithm used to lower volumes. In a way, I just want something that sounds like on CD in a car or when converted to FLAC & played on my Digital Media Player.
 
 

The plug-ins I use in my final mastering chain are not always for enhancement, they're for monitoring and judging the levels coming in and out of my speakers. 
 
I may use a Goniometer or correlation meter to judge the phase of the audio, sometimes raising the volume and metering that aspect lets you know where to tighten up or de-emphasise certain aspects. Like a wide stereo reverb, that may benefit from gating at the lower levels for example.
 
Plug-ins I use vary from project to project. However I do have go to plug-ins.
 
VSL  Suite Multiband
UAD Precision Multiband
UAD Precison Limiter
Waves J37 Tape
SSL G Compressor
 
No particular rhyme or reason. I like what they do.
 
 

External (3rd party) mastering used to get another pair of experienced ears onto the project. That by itself made sense to me ...

I still believe in the ears thing, don't want the algorithm thing ... that's too much one size fits all IMHO

yet for most of the online mastering services you won't get much of that golden ears time. Just look at the (low) rate you pay and do the math how quickly it needs to be completed to be a profitable business. That also applies to big outfits like Abbey Road. Despite higher few fees I would not be surprised if most work is done by juniors, assistants or whatever they call it

I just know if I could do better if my sound image was correct. So i'm just not banging my head against a wall metaphorically. 

OK so I tried a PAYG master from Cloudbounce using some of the magic options. First problem with the Chrome streaming playback for me. However I went and processed it anyway. Statistically it's mentally loud. 
 
https://drive.google.com/file/d/0B4bhVdNls9c4aG5LdjBQMzl3RTQ/view?usp=sharing
 
The dBTP is louder than expected. Even if I did process that as trance with stereo imaging options. I will upload the cloudbounce version to my soundcloud and you can find the original on there too. Which leads me to believe you really need to crush the living daylight out of your premaster before you even think about processing it.
 
I'm not happy with the results. Surely my mixing isn't that bad..sheesh!
 
 

Pre mastered mixes do not have to be crushed.  That is something that manual mastering can accomplish that probably automated mastering cannot.  I can take a -20 dB FS rms premastered mix and bring up to -8 dB rms if I wanted to.  But in stages and carefully.  Trying to slam whole -20 mix up by say 12 db in one process is not actually possible and still sound great.  With the automated processes it may possible but it sounds terrible usually in the making.
 
If I am wanting a very loud master there is nothing wrong with creating a slightly louder pre master.  K System -12 is a good level for this.  (this can involve some form of stereo buss compression too, but not heavy, just conditioning) But if I am not sure if I want a -12 pre master then I can go for a lower unmastered mix such as -20 and do the work to bring it up later. 
 
Automated mastering may require a different premaster level perhaps.  Only experimentation will tell.  There are still so many deficiencies with automated mastering though compared to detail ears driven manual mastering.  Don't confuse the two.  They are nothing alike.  As long as you are referring to automated mastering processes.  Careful manual mastering is in a class of its own.  Especially when it comes to transforming a transient and delicate -20 mix into a wall slamming monster.  And still sound great and punchy. 
 
There is less need to be pushing to super high levels.  Maybe the automated mastering processes are already behind the times.  The streaming sites will turn them down in the end and make them sound whimpy.  There is a balance point.  e.g. A -14 dB FS rms master hits the almost perfect -16 LUFS spot which is much more in the ball park now with many streaming services. 
 
There are have been numerous articles on this subject.  Especially a featured one in Sound on Sound recently.  The trick is the various streaming sites all have slightly different approaches to levelling out music.  You almost have to master for them individually.  Some software mastering plugins now incorporate different streaming algorithms. And let you hear them in advance now too inside your DAW.  Do some research in this area in order to improve how your music sounds in these environments.  Instead of sending tracks off to some random automated mastering service where have no idea what they are actually doing to your music.
 
Upload the finished file somewhere from one or some of these services and I will open it up in some detailed editing software.  I can tell if it is mastered well or not. 
 
A really great mix will master very well and it always comes back a step to getting that mix sounding great and well balanced in the first place.  Just the right amount of energy across the spectrum.  Keep the bass under control too.   You can master your own mixes, you just need a week off between the two processes that is all.  In fact if you are mastering your own mix you can bring a level of mixing detail into a mix with mastering in mind.  But you don't do it on the same day at the same time though. 

I tried applying a similar amount of gain using the sonar tools. If you look at the Google drive link you can see what they did.

I might try to address the mid-high distortion aspects which are occurring. It means finding the project again. My top 4 tracks are my recent projects since I started getting back into Sonar production. 
 
Everything else is old and deprecated really and need done again, if I can even find the original projects.