Cactus Music
Listening to the tracks and also LOOKING at the wave forms I think your suffering from not so much the recording part, but mixing and mastering. Your songs are a little out of balance and the overall level is weak. 
LOOK at a commercial recording of that style of music and you will see the waveform is a solid brickwall. There's no room for dynamics in pop music. ( and even country now) Slam that puppy with your mastering tools and get your average RMS level around -12db. My guess is your 10db away from that goal. 

 
Thanks for listening. I'm currently uploading my new mix of the Shubidua cover (.Wav this time zzzz) .Allready better than the prevous.
I guess that's why my Landr versions is always much louder. After exporting I have been using Audacity to normalize and thought that might be enough.
 
 

Oh, and on the topic of vintage synths, I was making a track for Mony Mony and wanted a Jump kinda sound I must have spent way to long looking. I had to preview most all the soft synths that looked possible.  I was shocked at how bad a lot of the included stuff was, what is all that for??  Anyhow I finally found it in Roland Groove synth. Synth Stack. And even funnier was a great patch in  Good old TTS-1! Just crank the chorus up. 
Which brings up another point, if you want good synth sounds, you need to go beyond the pre sets and start editing. It's always been that way.

Yes, I know. I remember doing that on my old Korg Poly-800, but every synth seem to have a different set of knobs and it just takes time to get to know the impact they have. I have spend a lot of time looking for the right sound, unable to find it, so you're right.

SoundRegion
 
I guess that's why my Landr versions is always much louder. After exporting I have been using Audacity to normalize and thought that might be enough.

Normalizing isn't one of the things you do to get loud mixes. In the quest for loudness it's about meaningless.

I cannot recommend OP-X Pro II enough for "vintage" synth sounds. It isn't even very expensive and comes with loads of presets, both creative and modeled after famous sounds. 
 
As for brickwall limiting, PLEASE don't "slam" your track until it's a sausage. 

Sanderxpander
I cannot recommend OP-X Pro II enough for "vintage" synth sounds. It isn't even very expensive and comes with loads of presets, both creative and modeled after famous sounds. 

I checked out OP-X Pro II and it sounds pretty impressive (listen to the preset demos here). The way they list the price is a bit confusing though. Is the "special" price $179? Right now €85 is $96.

   When you are writing MIDI files, you have to understand that there is a variety of information beyond the "note on" and "note off" information.  Most good samples, including those in Sonar, will sound different based upon intensity of the note (how hard you strike the key), aftertouch (key holding force), portamento (sort of a note-to-note style) and many other functions of the sample library.  You can see some of this info in various windows of Sonar, including right clicking a MIDI note. 
   Sonar can be pretty difficult to do phrasing as its MIDI editor windows are limited.  I did this version of "Sing, Sing, Sing" with Sonar (back in the Cakewalk 9.0 version) by right clicking each note and entering a mathematical beat map I created on paper (I also used Cakewalk to record and add the sound effects to make it sound a bit dated.  The synth is just GM.  This project took 6 months!)...
https://soundcloud.com/bassic-productions/sing-sing-sing-with-a-swing
   I did a study of John William's "Raiders of the Lost Ark" music using Finale to create the MIDI file and recreate an actual musical score.  I then imported the MIDI file into Sonar for mixing and mastering.  I used Sonar's version of the Dimension Pro synth with their basic samples.  Again, many notes needed to be modified to create the exact sound to match the original orchestral players.  It also meant that most parts needed to have different MIDI channels to create the sounds a single instrumentalist would just do in performance (this project took about 4 months)...
https://soundcloud.com/ba...aiders-of-the-lost-ark
   To sound professional, you will still need skilled editors, mix/mastering engineers and all of the work a standard "real" recording production would require.  "Virtual" orchestras are no different.  Sonar is an excellent DAW but it can't replace any professional musician, engineer or producer... it is just a tool.

SilkTone

Sanderxpander
I cannot recommend OP-X Pro II enough for "vintage" synth sounds. It isn't even very expensive and comes with loads of presets, both creative and modeled after famous sounds. 

I checked out OP-X Pro II and it sounds pretty impressive (listen to the preset demos here). The way they list the price is a bit confusing though. Is the "special" price $179? Right now €85 is $96.

Oh huh 179 sounds more than what I paid. Was more like 80 euros. Totally worth it though. 

Recording is an art and a science.  If I gave a friend of mine the same software (Sonar) and all of its resources, I can almost guarantee that he would not achieve the same results that I would.  I have been recording for decades and am still learning how to improve my sound and mixes.  
 
Cheers!

If you can post the song on SoundCloud and then share the link, maybe I will have some ideas.  Or maybe we will all think it sounds great.

I agree with Konrad. Upload to SoundCloud, (and maybe share here http://forum.cakewalk.com/Songs-f89.aspx)
and link that song to this thread. That way you will get more than "just our" feedback. There are a lot of very good and helpful ears here
All the best.

konradh
If you can post the song on SoundCloud and then share the link, maybe I will have some ideas.  Or maybe we will all think it sounds great.

What happened what that I got the idea to finish some old project that have been on the harddrive for a while (some up to 18 years), because they needed someone to sing, but I decided to sing myself, which is something I have not done and it's obvious why.  A while after the upload to Soundcloud I decided to play them on the big stereo and was very dissapointed. An example:
 
https://soundcloud.com/soundregion/bageren-og-servitricen-shubidua-cover
 
I thought the drums sounded fake, the vocals were muttled and not clear and the powerchords and string were almost inaudible. After the advise given here, I tried to mix using the JBL encounter speakers instead of the headphones:
 
https://soundcloud.com/soundregion/bageren-og-servitricen-new-mix/
 
Still not perfect, but a definite improvement. I tried Landr, but I think it leveled it out too much.