That works, but the HackRF isn't really clean enough for serious use. I have a lash-up here that does a couple of Watts with a HackRF and LOTS of filtering, and can radiate my little 8 stereo channel multiplex a kilometre or two around here. It was just lashed together to see if I could get it going (I was more interested in the DABMUX end of the software than anything else), but I did run a little extra DAB bouquet around here over Christmas and New Year!