Break in period for Solid State pre amp

I just bought one of the Sunfire Reference preamps advertized on Audiogon. I was somewhat less than overjoyed when I set it up and listened to it. I start off with the Eagles Desperado CD which has a wonderful cut of Doolin Daltons where the guitar transients just jump right out of the speakers. The transients were just not there. Almost sounded like the guitar was coming from the next room. The voice sounded hard and hollow instead of full and warm. Soundstage was somewhat smaller. I am comparing it to a B&K PT3 MK2 which is a much less expensive piece. The B&K sounds warm, sweet and open with a huge soundstage.

However, Since the Sunfire unit is brand new am I being fair in my judgement. I was going to sell the B&K as I wanted a preamp with a phono stage and the Sunfire seemed like it was too good to pass up... How long does a preamp take to break in? Are there significant sonic improvements once this occurs?

Your responses are greatly appreciated....

Eagleman

system:
B&K PT3 Mk2 preamp/ Tuner (Old)
Sunfire reference preamp(new)
B&K Refence 4420 Amp
Adcom 600 CD
Thorens 160c, Linn basik plus arm Goldring 1042 Cartridge
Vandersteen 2CE sigs