Hafler DH300 Monoblock forever?

Hafler made a bridging kit for the DH-200. You can find the manual here: ( http://www.hafler.com/techsupport/pdf/DH-202_PC-7_bridgeKitForDH-200.pdf ) Your amp probably has this installed. If you can recognize the circuit(the PC-7 board), inside your amp: reverse the install procedure, per the manual.

Thank you. So, it sounds like if it has the PC7 board in there, it replaced what was there originally for that channel, and I'll need to find another board to revert it back to the original condition it was in as a DH-200, correct?

No! Both active component boards(PC-6) of the original DH-200 will still be in place. The PC-7A(bridging circuit) is a separate, much small board, that should be located/mounted on the rear of the right heatsink, it's components facing to the rear of the amp.

There is no PC7 board, just the regulat PC6 boards like my DH-200 has. It looks like it's wired the same also, the only difference I see is the input jacks are like those you'd find to plug full size headset type plug into, not phono jacks, so the also don't have the 2.2 ohm resistor attached to them like my phono jack inputs on my DH200. I can say this much, the chassis and faceplate for rack mount, both have silk screened DH-300 on them so it may have started life as a true DH-300 and maybe someone has already reversed it and removed to PC7 board....? I'll have to get a plug like these and get soem signal into it and see what it does.