How do I bridge a ML27?

I don't think you can bridge this amplifier. Is there a switch for bridged mono, a label on the rear panel with a diagram on bridging, or anything in the manual?

Cathode,
Yes, you can. I used to own one and the manual tells you how to do it. But you need to have special cables to do it, as the unit had camac terminations, rather than RCA terminations. (The locking camac terminations were a good idea that just never caught on.)

You'd need to speak to Mark Levinson (Harmon) about getting the cables with camacs. (But I don't "think" that the camacs are available even from them anymore, as I believe they quit making them many years ago. Which means either buying the camac terminated cables, or adapters (camac to RCA), second hand. I recommend getting the adapters, as they will allow you to use a variety of cables.)

Or, if your unit has XLR connectors, (mine did), you can have special (i.e. short) balanced cables made up for you by virtually anyone.

Be careful when you do this though, as your speaker impedance may cause your amp to become stressed, and cause it to run hotter than it normally would. (I don't think I would do this if your speaker's impedance is lower than 8 ohms or so.)

FYI: Here is a definition for bridging that I found on Audio Asylum's FAQ.

Bridging (also called monobridging or monoblocking) is the summing of two channels of an amp to give one higher-powered channel. An amp normally rated at 100W might deliver 300W to 400W when bridged. Because of the summing however, the load on the amp is seen as half of its normal value. In other words, an 8-ohm speaker becomes a 4-ohm speaker load, and a 4-ohm speaker becomes a 2-ohm speaker load. Speaker impedance ratings are nominal only. Actual impedance may dip to a much lower value through part of its range. When an amp's current load has been doubled due to bridging, it can often fail to provide the required amount of current into the load. Sonic effects include harshness in the midrange and highs, and thin bass. In almost all situations therefore, biamping with similar amps will result in better sound quality than bridging. Bridging is best left to professional sound-reinforcement applications, where sound quality is secondary.

Good Luck!

Google RCA to Camac adapter.

Thanks for the inputs.
It seems to be awkward to bridge this amp hence I'm going to put this plan on hold... maybe I'll get a 23.5 in the meantime.

Other than that, can anyone tell me what connectors fit the sockets above the Carmac sockets on the 27 (where it says "input" on the diagram on the back of the amp)?

Thanks.