I believe Unsound has provided you with good info. When considering an upgrade it is best to have defined what improvement one is looking for. If you are happy with the 140 and it drives your speakers to your satisfaction then keep it. Enjoy!
B&K ST-140 vs 200.1 mono blocks
I currently had a B&K ST-140...the last version with blue and red lettering, have them on a pair of Castle Inversion 100 speakers 8 ohm, preamp is Melos Reference MA-333, it sounded wonderful with "tube" like sound. Just wonder how will the B&K 200.1 mono blocks compare to the ST-140? You advise and opinion much appreciated!