I did a little digging and found a FCC spec sheet posted on the other site by satgirl51 . Since it mentioned modulation compatibility with MxL568, I did a little googling and think maybe what the HR54 uses may not be Broadcom's chip but could be Maxlinear's MxL581 which also supports 8 demodulators. Its timeline would fit with the HR54's, but like Broadcom's 8 tuner chip has no mention of support for bonding and was designed too early to support DVB-S2X. Whichever it uses, it either has unannounced support for bonding, or that is being handled somehow in software. Since these full spectrum capture / full band capture chips basically work as big DSPs, they are pretty programmable. Not enough to be made to support DVB-S2X, but likely enough to support bonding.