I don't have any experience with the TFM-6, or any TFM under the TFM-35, but the TFM-6 is NOT a magnetic field amp (triac controlled mag coil) it is a more traditional transformer design. The only TFM's that are mag coil are the 42/45/55 and 75.Bridging in general is not very well thought of, although it would be easier on the amp with those LaScala's (they're an easy load). The trouble is, when bridged, one channel is inverted, and you hook one speaker up to BOTH hot terminals. Now, instead of (for example) a 50 V swing, there's a 100V swing, which implies more power, BUT, to deliver twice the voltage, the amp has to be able to supply twice the current (not many can).
Delivering twice the current into an 8 ohm load is roughly analogous to having to drive a 4 ohm load (which is the wrong-headed idea that the amp 'sees' half the load comes from). If you bridge and try to drive a 4 ohm load, the amp has to be capable of driving a 2 ohm load, continuously.
This is the problem, then. You're now asking the amp to deliver twice the current to hold up the rail voltage, which it has a hard time doing, so the rail sags, and cone motion control suffers; IMO the sound is a bit 'loose'.