Tube or not to tube?

I would suggest that you go with an all tube integrated first . Then you can compare it to your present SS system and make a decision . I think that doing the hybrid thing or tube-pre and mosfet/SS amp will put you only part of the way there . Experience both 'extremes' and then adjust back to the middle ground , if you desire !
The Prima Luna Prologue 2 is a good decision as the maintaince thing is virtually nill with the auto bias feature !

go with tubes. an mfa luminescence and a cj mv125. this is tube heaven with lots of body, lushness and color, like a carmel sundae with whipped cream.

Musicrover..the rogue preamp is a good one. There are many other brands, tube equipment these days is all made pretty well, since they appeal to the highend ($) crowd. We carried conrad johnson..a very good brand. I think one of the best values out there is a Conrad Johnson PV10..used, as they are no longer made. I would focus on looks, remote capability, and try to find a good review on it.
As far as the amp... bipolar amps are usually built to amplify current..they sound powerful, usually at the expense of ultimate warmth/musicality. Your NAD is this type I believe. MOSFET amps usually amplify voltage, which makes them sound more warm/musical at the expense of ultimate bass power performance. MOSFET is similar in this respect to a tube amp.
To illustrate this point..Conrad Johnson makes a solid state amp MF2500 which uses MOSFET input stage and bipolar output stage, this amp reaps the advantages of both types of transistors. This amp sounds awesome..I preferred it to the Krell and Linn amps we sold. Most amps have the input and output stages consisting of the same type of transistor, the MF2500 is rare in this regard.
I read about the NAD 272 and it has input level controls on it! This is perfect for matching it to any tube preamp. I would buy a nice tube pre, connect it to the NAD, adjust the NAD level controls down so the preamp volume knob is turned up as much as possible during listening. This will give you the best dynamic range. Normally, you have to be a little careful when matching different brand preamps and amps because of this issue..but your amp has variable inputs so you're golden.
You can replace your amp with a MOSFET type..this will be more tube like. I believe a single ended MOSFET amp is a class A type...which will sound better than a class A/B type, but total output power will be lower with the class A and will be hot to the touch, warm up your room, and waste power.
We had people return tube amps saying they didn't have enough power (bass) for their needs. If you listen to classical/jazz and have efficient speakers, tube amps will do fine. If you listen to rock/dance and have inefficient speakers solid state amps will do better. System matching can make or break a system.
Hope this helps. Enjoy your adventure!

Thank you Christobl, All that information is helpful and thanks again for the time. I think after all the input I am going with a used Jolida 502b (Found a great deal) and give tubes a try, My thought was (prompted by Saki70) to go all the way with a small budget unit and see how I like the sound. I also like the idea of listing to the unit for awhile and maybe trying different types of tubes. I am fortunate enough to keep my NAD system and try something new and or perhaps sell some of the equipment at a later date or keep it and build a second system.

The jolida stuff is actually wonderful sounding. You will be stunned at the difference compared to NAD. Enjoy the tubeness..many never go back! :)