You will need a transformer of at least 6 amps rms to supply a 5 amp squarewave, likely more like 7 amps minimum. You'll also need a very large filter capacitor for the supplies, much more than the 2200uF on the PCB.
Also you'll need a massive heatsink, which the Amazon link doesn't show, the one we utilized has a small heatsink, too small for your requirements tho.
As mentioned above, the TDA7293 uses a "Bootstrap" technique to allow higher output voltages relative to the supply voltage, this won't work well at lower frequencies and certainly not a DC. Recall you'll need to remove the input AC coupling to the TDA7293 for DC use, pay close attention to the input DC offset. Also note the
true power rating, it's not 100 Watts!!
Study the data sheet carefully as these weren't designed for DC operation, so likley some issues will arise.
https://www.st.com/content/ccc/resource/technical/document/datasheet/4f/18/a6/c8/21/33/41/8d/CD00001887.pdf/files/CD00001887.pdf/jcr:content/translations/en.CD00001887.pdfMy recommendation based upon these limitations and your requirements is to get a pair of 8~10 amp high current bench power supplies (the cheap SMPS types will probably be OK), one for the + supply and one for the - supply. Adjust the current limits to just over the expected load current and the voltage limits just enough to supply the load voltage at the load current, this should minimize the TDA7293 power dissipation.....which will still be quite high and require a massive heatsink.
You should consider getting a few of the TDA7293 PCBs as likely you'll smoke a few, they are cheap tho
Also, take a look at the LM3886, this
is a DC rated Power Amp type.
Good luck!!
Best,