I definitely agree. 

This is just a hunch, but the AlphaCM synth may be responding to GM patch data embedded in the file. Those MIDI files are almost invariably General MIDI.
Expand your MIDItrack to show the Bank and Patch boxes.
In X1 Essential I have to select All at the top of my track view. MC6 should be similar.
If there are values in these boxes, change both to None. This may help.
In the case of the Nexus6, it probably does not respond to GM commands, because they are simply not relevant to it. This is true for the majority of soft synths.
By the way, I may have to check that one out. I'm kind of a synth junkie.
I've noticed that the synths you have mentioned tend more toward synthy than emulation of traditional instruments.
Do you have a controller, or are you considering getting one?
The reason I ask is that, while the MIDI files you are using may work with these synths,playing them with a controller blows the doors wide open. Live interaction with the synths really reveals what they are capable of.

As for MC, I totally agree with Guitarhacker. It is very capable at a deceptively low price point. it's strong on its own, but with the addition of other plug-ins, you have a real powerhouse.

I meant to ask, is there anything in particular with Sonar that you now cannot do without?

Also, I noticed if you create a synth with a "Simple Instrument Track" it actually create two tracks which are hidden from view. If you then delete that synth from the synth rack, the underlying two tracks "pop out" (the audio and midi track) with a value of -1 replacing the synth assignment.
A bit of random useless trivia :)

You really can install too many VSTs. I haven't really done so yet, but I can see from the amount available that one has to be pretty judicious. I have to fight my natural inclination to install "all of them" just so that I can see what's there.... DANGER WILL ROBINSON!

Any time you delete a synth from the synth rack that has tracks associated with it, you are inviting a mess.
It's just bad mojo.

I personally do not like "Simple Instrument Tracks". They are intended to be "simple", but if you try to do anything moderately sophisticated, you are severely restricted. I think they were developed because so many new users were confused by the relationship between the MIDI source track and the synth audio output track.
The downside is that, while  a simple instrument track works, it does not promote understanding what you are working with.
Case in point.
Yes, you are limited in the number of synths you can insert in a project. I believe MC is limited to 8(could be wrong on that).
With simple instrument tracks, you are going to hit the ceiling really fast.
However, if you use a synth like TTS-1 to its fullest, you can have 16 MIDI tracks feeding one instance of the synth, and have 4 audio outputs. This is not possible with simple instrument tracks, but is very easy with separate MIDI and audio tracks.
That is my preferred method, because you have much more flexibility and control.

I'm gonna have to spend more time with TTS-1 for sure. Thanks for the tip.

Great information there.

I started out years ago trying to do this right, by buying the right tools.....software DAW, interface, monitors, computer.....then I started to grab lots of "free" VST's and synths from the net. 

Pretty soon I had a sizable collection of mostly mediocre stuff. Really not much better than the TTS general midi stuff.  While TTS is an amazing synth and is capable of running 16 tracks with 16 different patches at a time, the sound quality, unfortunately is on the lower side of the bell curve. (for my needs and concerns)

I have heard some really amazing things from people who take the time and work with TTS to create a masterpiece. 

So, when I finally decided to build a DAW and move from the laptop to a custom machine, I also had a serious look at the synths and FX I was actually using, and I migrated only those VST's to the new system. 

Somewhere along the line I decided to buy the Native Instruments Komplete package of synths and BiaB.... not cheap but definitely some high quality and good sounding stuff....it came to the new machine, and I had purchased a few other fairly nice tools, and they too were migrated over. Included in that are Melodyne, and Ozone. Both are FX. I occasionally use some other things but these are the main ones. 

All of the free stuff stayed on the lappy since it fell into the category of rarely if ever used. I do not miss using the SFZ and TTS patches and sound fonts. 

Now, I have a small selection of synths and FX that I use. These tools are used on just about every song I work on. These  things are the mainstay and the foundation for every project I work on. With them, I can do everything I need to do, and everything on my songs page is created and recorded with them.....and with a few live instruments that I play, such as the occasional piano part, guitar parts and mandolin parts.... plus vocals. 

I'd like to get to that stage eventually.

I think I am definitely gonna resist the urge to "try new stuff" ALL the time (which tends to be a habit of mine).

The TTS-1 didn't take long to learn at all. I found the 5 minute youtube intro on it and I just realised it was a General MIDI synth module. Sweet. This is perfect for me because I have collected lots of MIDI songs over the years which are all general midi. (I used to play them on my Sound Blaster AWE32). I totally get the whole 16 track thing and the STANDARD MIDI feature set (incl pan/reverb etc). Most of my MIDI collection is GM standard. Right now I am using them as practice, but also to get my kids (age 7 and 9) enthusiastic about piano practice. I can load a familiar MIDI song and they can record themselves. I just did this for the first time with my daughter this morning and she kepts saying "this is so fun".

So I am totally thrilled about the TTS-1. It is easy to use, and even for sketching out musical ideas, it is a good "bread and butter" toolbox of sounds to get going with. Whilst the quality may not be what most people need to record, I am impressed. This is so much better than the synths from back in the day - even though the TTS-1 is probably "vintage" by now (judging from the crappy interface). I just ran Eric Clapton's COCAINE song through it and the guitar solo at the end sounded surprisingly good. The whole thing did - drums included. For standard rock songs, it does alright. I swapped out the main guitar riff to run through Amplitbe (free) just for fun.

I really would like to know how the midi event filter works though. I am getting no joy with it.

I loaded up the cocaine song and tried to change the settings on track one. As soon as I play the track from the beginning it resets all the settings and loses my changes. I tried shortening up the clips but it makes no difference. I'd like to know how to weed out those midi instructions from the file.

[Cakewalk FX MIDI Event Filter]

Nothing I do seems to change the behavior of the midi clip data sent to the instrument (TTS-1).

Yeah, TTS-1 has been around for a while, but as you noted, it's a good bread and butter synth.
And it's hard to beat for playing those GM files.

Can you provide a link to one of the MIDI files you are using? It's been a while since I messed with them.
I'd like to take a look at one to see if I can identify the patch info.

Also, change the patch/bank in the MIDI track, not the TTS-1 GUI. The track settings will override the settings in the GUI.

Thanks Shimozu, I have sent a link by PM.