Somebody Help Convert me to tubes

I first want to thank everyone that has been so helpful over the years. This forum and equipment site has been great.

Here is my dilemma. The first bunch years in this hobby my taste (and perhaps ignorance) has led me to pursue every last ounce of detail from a system, but after spending some time with some tube product, I am starting to prefer the more "listenable" type of equipment.

What I am looking for is for someone to help me with a step in this new direction. I am thinking of starting with a new preamp. Please don't recommend dumping everything I have and start over, I can't afford that, and besides I very much enjoy my system and I am looking for small changes at a time and to learn and appreciate the differences. I am also looking for a piece that if over time I like the way my system was, I can easily pass it on to another A'goner. My equipment is as follows:

Thiel 2.4 speakers
ML 27.5 amp
ML 36S DAC
ML 38S Pre
Theta Data Basic II Transport
Kimber Select (1111 and 1120)
Transparent Plus Speaker cables
Synergistic AC Master Coupler on Trans and Amp
Transparent Power cords on DAC and Pre

Thank you for your assistance once again.