Is an unbalanced preamp a bad thing?

odd that all of a sudden you think of this.

how does the system sound ?    if it sounds good then leave it and don’t worry about it

+1 @riley804 There might be marginal improvement using balanced connections if both amp and pre are fully balanced, but I don’t think it’s worth pursuing if you like what you’re hearing now. 

some say they hear a difference between the two and how true that is , i don’t know.

is it worth selling the preamp you have and then finding one that is balanced?    the new preamp might not have the same sound so you have to deal with that and also finding cables that sound good also.

i thought (?) the purpose of xlr was for longer runs that rca can’t do ?

i would keep what you have

I am borrowing a Conrad Johnson preamplifier and it sounds very nice but to my surprise I couldn't use XLR cables.  If I wanted this preamplifier I would have to go through all the torture of selecting new cables versus XLR cables I already have.

Fortunately I don't need extended Cable runs and it's supposed to be a really good preamp so maybe I'll buy one.

Also borrowing some very nice speakers called Magico and will listen to these for a while until I have to give them back.  It's nice having friends who have Nice gear.

Like everything it depends - in this case, especially on the downstream component and how it handles SE vs. balanced input signals. Sometimes there is an extra stage for SE vs. XLR (or vice versa) that the signal has to pass through. It can be an opamp or transformer, which is definitely going to impact the sound. Best is a differential input stage, which doesn’t care whether the signal is SE or balanced.

If cost is not an object and you can avoid the pitfalls, fully balanced has advantages, but it requires doubling the circuitry and (almost) twice the expense.

For headphone amps I find balanced drive to be extremely effective, because it grants +6dB extra gain, up to 4 times the power, and double the slew rate along with common mode noise rejection. And Stax/electrostatic headphone amps have to be balanced anyways, and they sound the best (for other reasons too). For straight preamps, the advantages of balanced drive are going to be of much more subtle impact.