I don't think that break-in is your problem. Suspecting as much, I read the user manual (online) for the Clearaudio Balance. It clearly states that the factory setting for the the phono-pre is 47000 ohms and that if you want to change it you will have to select your own resistor values. With the factory setting, you are very likely to get a bright presentation, especially given that the recommend impedance is MUCH lower, ~100 ohms. Here is the text from the user manual:
"Factory-made, the input impedance/capacity is set to 47 kOhms/100 pF for MM-Cartridges, but you can set the input impedance for any cartridge, by using the 5-pin binder-connector or the socket R101 on the circuit board of both channels. If you use the binder connector for your tonearm, then take socket R101 to set the input impedance. For the
input capacitance is socket C101 on the circuit board, if you need an other capacitance, you have to change the condenser at both channels." (admittedly, rather garbled English, don't you think?)
There is a circuit diagram in the user manual that indicates where r101 is so that you can solder in the appropriate resistor. (Don't worry about the capacitance...)
Kudos to you ears for telling you that something was not up to snuff. I often wonder how many people make pronouncements about a cartridge's characteristic sound without knowing that for MC's, proper loading is very important.
BTW, I am using a prototype of a phono-pre that a guy that I know is building. I generally have used tube phono-preamps with step-up transformers. His solid state circuit has replaced my tube gear and I have not even thought once about going back to the tube gear (still use my tube integrated amps though). His circuit has three different gain settings and probably about 100 different impedance settings that can be selected via dip-switches. Using this preamp, it was a breeze to dial in the loading. The last preamp that I could do this with was a Pass Aleph Ono. For my tube preamps I had to calculate the impedance in relation to the step-up tranny impedance and solder in the appropriate resistors. So, besides the phenomenal sonic performance of this prototype, I sure like the convenience. If you have any interest in this phono-pre, feel free to email me.
Best regards, and good luck