Is an unbalanced preamp a bad thing?

Absolutely do not worry about it. Balance or not balanced is a design choice… I have had both and intermixed them. Typically there is virtually no difference in sound quality… Conrad Johnson components are incredibly good sounding… I would not think another moment about it.

I own Audio Research Reference gear and have tried to tell the difference between single ended and balanced… and could not.

Conrad Johnson is one of the greatest audio companies in the world producing some of the most musically satisfying components available. Enjoy!

Is an unbalanced preamp a bad thing?

its terrible, safety hazard! have fire extinguisher and nomex suit ready....

Some people actually prefer RCA over XLR. Keep in mind, just because there is an  XLR connection, it doesn’t mean it is truly balanced. 

It depends.  If the balance of your gear is fully differentially balanced then you will typically find some degradation in sound quality if you use the single ended inputs and outputs.  Examples of this where it really makes a difference are brands like BAT, Ayre Acoustics, Esoteric, etc...  If your system is not differentially balanced, the gear simply offers XLRs, then usually you will find the RCA connectors will sound as good or better unless there is a bad noise problem.   

And there in lies the huge challenge manufacturers don’t really explain it very well. They say it’s balanced but then again is it really truly balanced for purposes of determining if it’s better to use XLR’s or a simple RCA connection.

This is why people can’t stand buying new equipment with these stupid challenges.

Conrad Johnson I guess makes a really good product but they don’t use XLR. The streamer i use recommends XLR, a lumen. So wtf should you do? I guess you need to buy really good RCA cables to address any deficiencies. And the rabbit hole gets deeper