What interests me about this chip, as well as being a high powered 10W audio Amp, plenty of circuits which are available on the web. The TDA2003 has also been used in VLF PA design Amateur projects. From G3XBM: https://sites.google.com/site/g3xbmqrp3/vlf/8-97khz-earth-mode-transmitter
Also at 73KHz The Heyphone John Hey (G3TDZ):
I emailed John recently about the TDA2003 and he reckons that they will work at 137KHz depending on manufacture? Time to get testing a few on the end of a signal generator..