Do I need a balanced preamp?

My dac, preamp, and amp are all fully balanced circuitry, and I noticed a big improvement when I switched to balanced cables. Now, I am considering a preamp that is not balanced (Supratek Chenin - I've heard these are killer). If I do that, my understanding is that I won't be taking full advantage of the dac's and amp's potential, even if I use balanced cables from the preamp to the amp (the preamp has balanced outs even though it's not fully balanced circuitry). Will this mean I will have to once again look for a new amp? Is this idea nuts? BTW, the front end and amp are both Theta and current preamp is Simaudio P5. Thanks. -Dave
What you have heard about your gear is probably correct- that is common with balanced equipment. With the single-ended preamp, you will loose the ability to run long cables and the cable selection will get more important to the overall sound.

You do not have to replace the amplifier though unless you are looking to upgrade- but I would not do that until you have had the new preamp long enough to be sure its broken in. The amp will work fine with it.
While it is nice to have a balanced signal all the way from source to speaker, and you will lose that aspect with the Chenin, it may turn out to be "one step back and two steps forward." if the Supratek is that much better than the Simaudio. Hopefully you don't have to sell the Simaudio to get the new pre. Only you can decide if you have moved forward.