Double check you speaker impedances. As well as what’s been said about, the power tubes are suspect when amps lose low-end all the sudden.
I have a 2014 BE that has prominent low end girth and thump. But it’s a little too much and when I have it modded I’ll have Dave dial some out. So my thoughts are that every BE I’ve played has sounded just like mine with more than enough bass and you should do the basic tube amp troubleshoot and maintenance. I’m not directing this towards you OP, but for those who don’t know what those basic tube amp troubleshooting steps are, by now they should.