So after some playing and testing, I'm reporting that I found a couple things that are interesting.
I followed Marco's advice and swap the V1 tube for an old Baldwin I had laying around, great tube. I actually took the 3 tubes of the RM4 out and just used the V1 since the other 2 are for the fx loop output. This made a lot of difference and the feel is there right where I was expecting it to be initially.
The RM4 definitely sounds better with the modules open (each module about 1 or 2) AND with the RM4 master output at about 1 also.
Thanks Marco!!
While doing this tube swap I found out that looking at the RM4 from the back, V1 is the one on the bottom, the one to the top right is the pre loop output and the one to the top left is the post loop output. At least that's what it seems to be since while testing the V1 without the other tubes the volume dropped considerably.
Now, this is where I think I had the problem, as I am trying to maintain the same output level as the other preamps so I can switch back and forth between them, I had to keep the RM4's master output really low as it is REALLY LOUD compared to the MP1, Hence why I'm using the Rocktron to control the level of each preamp.
So to overcome this I'm using the fx send of the MP1 set at max and the Rocktron's ouput set at -10db, this way both preamps have the same overall output feeding the Rocktron while maintaining the modules' and the RM4's ouputs at 7 o'clock and giving me the option to control the input to the 5153's fx return with the Rocktron's output level.
At this point I reckon that someone will say why don't I get a line mixer, well I'm actually trying to downsize and I don't want to get more gear with lots of cables and connections etc. My goal was to have the RM4 replace my Quad and the MP1 and use the 5153 as a power with the option to use it's own pre of course. So far the Quad is out already, anyway this would make a discussion for another thread I guess.
Nightdare: Thanks for the HUSH advise, the HUSH was already off in all my presets and above that I run the Rocktron with the PRE hush routing, so I believe this wasn't the problem, specially because it's the exact same way I use it for my other preamps.
Suphuckers: Indeed, seems that the other modules are not for me.
Now a new question arises: Is there any pro/cons to run the RM4 with ONLY the V1 tube? I don't use the fx loop of the RM4 and the lower output without that output tube seems to work better for me.
Any thoughts?
Thanks for all the comments! They have been really helpfull.