It takes between 40-100 hours for the amp to "burn in" - so be patient my friend
You could let it play with a CD/MP3 player and a perhaps a dummyload on the speaker out a let it play for a few days.
I made the mistake a made a zillion mods to my amp, right after I finished it. I did so because I too was disappointed in the amp. But, rest assured it will soften after burn in period.
You should try to adjust the internal trimmer to 8:30-9:00 - put it way down low, and you will find the sweet compressed tones og Larry C and Robben F