TRACON'S XMITTER FAILED. ACFT BEING VECTORED FOR A RWY 9L VISUAL FLEW THROUGH FINAL APCH COURSE AND CONFLICTED WITH ANOTHER ACFT ON FINAL FOR RWY 9R.

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INBOUND TO MIA FROM APF ON SCHEDULED COMMUTER FLT. WE WERE 3000 FT MSL ON RADAR VECTOR FOR VISUAL APCH TO 9L AT MIA. AFTER SEVERAL HDG CHANGES AND A CLB TO 4000 FT FOR RESEQUENCING ON FINAL W OF MIA; WERE IN A TURN FROM N TO S WHEN HANDED OFF TO 124.75 (A DIFFERENT APCH FREQ). THE OTHER CTLR DID NOT ANSWER MYSELF OR 2 OTHER ACFT THAT WERE TRYING TO CHK IN WITH HIM. I IMMEDIATELY SWITCHED BACK TO FIRST CTLR AND MONITORED SECOND CTLR (124.75) ON #2 COM RADIO. WHILE THIS RADIO CONFUSION WAS OCCURRING; WE CONTINUED OUR LAST ASSIGNED ATC INSTRUCTIONS. IN DOING SO; WE FLEW THROUGH THE APCH PATH OF BOTH PARALLEL (9L AND 9R) RWYS AND PASSED DIRECTLY IN FRONT OF AN ACFT ON FINAL AT OUR ALT. WE ENSURED SAFE SEPARATION AS I REGAINED CONTACT WITH 124.75 MHZ CTLR. APPARENTLY; HIS XMITTER WAS OFF THE AIR FOR ABOUT 1 MIN. THERE WAS NO MISHAP; BUT THE POSSIBILITY FOR A MIDAIR WAS GREAT IN THESE VMC CONDITIONS. I BELIEVE THERE WAS AN EQUIP PROBLEM WITH ATC AS WELL AS A HDOF MADE AT A CRITICAL TIME THAT MIGHT HAVE BEEN AVOIDED. CONFUSION RESULTED; TO SAY THE LEAST. WE LANDED SAFELY ON 9L.