It looks like you also may need a receiver with speaker-level outputs for the subwoofer. Those are also few and far between. An Onkyo that came with the HT-3400/3500 is the only one I can think of. Yamaha might have something. Or a new subwoofer that works with the new receiver.
Receivers that are listed as 4 ohm compatible and can safely power 4 ohm speakers tend to be very pricey. But it would be kind of silly to pay $500+ for a receiver to power htib speakers. Either find an older high-current receiver off ebay/craiglist or toss the whole thing and start over. That's one of the many reasons htib's aren't recommended too often around here, or anywhere else. One part breaks and the you most likey have to chuck the whole thing.
Edited by gene c, May 12 2013 - 09:27 AM.
"Everyday room": Panasonic 58" Plasma, Dish HD DVR, Pioneer Elite vsx-23, BDP-23 BR, dv58avi universal dvd player, Dynaudio Audience 50's, 40's 122C, Dayton HSU-10 subwoofer.
"Movie/Music room": Toshiba 65" DLP, Dish HD receiver, Adcom GF-700 5.1 receiver, OPPO BDP-80 BR player, Polk LSI25's-LSi7's-LSiC, 2 original Dayton 10" "Mighty-Mites" subwoofers. (subject to change without notice).
Also have...too much to list. Help me.