A single 30w per channel U70 would not be enough power for the HT3s in a music applicaiton where you wanted all of the dynamic range done realisticlly. However for essentially TV sound (coming off the analog audio outputs of my cable box) which is either compressed, or on movies either always too loud or too soft and needs watching with the remote volume control in hand, a single U70 is just fine, as long as you don't need the bombs going off at wall rattling levels.
Now two U70s bridged with our Ultra Bridge will give you over 100 watts per channle into the HT3s and that is a different story all together.
Of course a Fet Valve 350 or 550 works super great too, but I don't have a spare one of these available right now for my own use, darn it.
Frank Van Alstine