I have been trying to get my soft synth arpeggiators (cream, obelisk) in Sonar Platinum. In order to feed an arpeggiator via a soft synth the soft synth has to have a midi thru. Many soft synths have midi output indicators but don't actually output midi. 
 
Anyone out there. What soft synths have midi outputs? Real ones. 
 
 

I merged this with the 3rd thread you have created on this topic. Please stop creating new threads about this.
 
You have the signal flow wrong. The flow is
arpeggiator > synth
NOT
synth > arpeggiator
 
The only VSTi that needs to pass MIDI through is the arpeggiator VSTi and to my knowledge all of them do

Bob In Portland
Scook, what soft synths actually have working midi outputs?

I can confirm that Meldaproduction Mpowersynth has working midi outputs. When you configure an arpeggio in Mpowersynth, you can send the MIDI out from Mpowersynth to another synth - like Rapture Pro for example.

With this configuration, Rapture Pro (or what ever other synth you like) plays the arpeggio notes as generated by Mpowersynth.

Okay, scook, so the midi information should originate on the arpeggiator track, which then is processed and sent to either a midi track hooked up to it or to a soft synth? Because that doesn't seem to work either. Somewhere in the many manuals and other informations sources I've been to or have been given I had to have a midi track, then a soft synth to feed the arp, then another soft synth to get the amended results. That didn't work. 
 
So I take a midi track and put the arp in the first track? Or do I take a midi track and have it output into another midi track goes into the arp which goes into yet another midi track which goes into a soft synth?
 
In other words, how do I get the midi into the arpeggiator? Since that seems to be the big problem here I need someone to explain to me how that is done, because all of the suggestions so far don't seem to work. 

Try the example msg #5 in a new project with no deviations. IOW add the arpeggiator VSTi as an instrument track. It is the only case that screams instrument track instead of the old audio/MIDI track way and simplifies the setup. How you add TTS-1 or whatever synth used to play the arpeggiator does not matter but the example above makes it pretty hard to screw up.
 
MIDI gets to the arpeggiator VSTi by setting your controller as the input for the instrument track containing the arpeggiator VSTi, by dropping MIDI clips in the track or directly adding MIDI data to the track using on of the MIDI views in SONAR. This is no different than any other synth.
 
When using Cream pay attention to the note range as the plug-ins uses the note data for a variety of things. Refer to the Cream manual for its MIDI note mapping.

I tried putting the actual midi notes onto the track that contains the arp. The midi notes are affected by the arp, but the midi doesn't seem to follow the path out of the arp. Also, I can't tell what is playing the notes. The synth that used to be on that track? 
 

The arpeggiator VSTi does not make any sound. Any other synth with its input set to Omni or the arpeggiator VSTi is making the sound. It seems to me you have still not followed the example provided in msg #5 in a new project. 

The data flow that works for me is:
 
MIDI keyboard ==> Chorder/Arpeggiator ==> VSTi (soft synth)
      (MIDI out) ==> (MIDI in) (MIDI out) ==> (MIDI in)
 
The photo below includes two instances of Cthulhu. I hope that doesn't make it confusing. It was just a test to trigger two synths.
 
(You'll need to right-click and open in a new browser tab for full resolution.)

scook, may be bigger problems. For some reason my midi instruments cannot transmit midi information into Sonar. No midi into Sonar, no midi into any arp, no midi out of any arp, no midi arriving at the final synth. 
 
So I couldn't repeat your #5 because I couldn't feed midi from instruments into Sonar. 
 
If there is a midi track with a hardware synth attached it seems to work. But not either Cream or Obelisk.
 
What could screw up midi inputs all over Sonar?
 

That's a basic set up issue. Your controller need to be set up correctly first so it's sending, this can be confirmed by looking at the midi icon in the lower tray or in my case a LED on my interface will light up. 
The track needs to have it's input set to OMNI and the midi device as input. You might need to go to preferences MIDI and select the device. 
 
Glad this somewhat confused thread came along as I was just going to read the manual about setting up an arpeggiator.  Seems easier that I thought.   I have never used one and have a song that this will be cool for. Thanks Scook , promidi and the maartian for your clear information as always.